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【327696】2022年湖南省郴州市中考数学真题

时间:2025-01-20 20:01:50 作者: 字数:19733字
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2022年湖南省郴州市中考数学真题

题号

总分

得分





注意事项:

1.答题前填写好自己的姓名、班级、考号等信息

2.请将答案正确填写在答题卡上



评卷人

得分




一、选择题

1.有理数 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 0 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 中,绝对值最大的数是(       
A
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
B
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
C
0
D
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>

2.下列图形既是轴对称图形又是中心对称图形的是(       
A
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
B
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
C
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
D
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>

3.下列运算正确的是(       
A
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
B
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
C
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
D
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>

4.一元二次方程 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 的根的情况是(       
A
.有两个不相等的实数根
B
.有两个相等的实数根
C
.只有一个实数根
D
.没有实数根

5.某校举行“预防溺水,从我做起”演讲比赛,7位评委给选手甲的评分如下:90938893859295,则这组数据的众数和中位数分别是(       
A
9592
B
9393
C
9392
D
9593

6.关于二次函数 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> ,下列说法正确的是(       
A
.函数图象的开口向下
B
.函数图象的顶点坐标是 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
C
.该函数有最大值,是大值是5
D
.当 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 时,yx的增大而增大

7.如图,直线 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> ,且直线ab被直线cd所截,则下列条件不能判定直线 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 的是(       
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
A
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
B
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
C
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
D
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>

8.如图,在函数 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 的图像上任取一点A,过点Ay轴的垂线交函数 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 的图像于点B,连接OAOB,则 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 的面积是(       
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
A
3
B
5
C
6
D
10

评卷人

得分




二、填空题

9.二次根式 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 中字母x的取值范围是__________

10. <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> ,则 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> ________

11. <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 关于x轴对称的点 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 的坐标是_______

12.甲、乙两队参加“传承红色基因,推动绿色发展”为主题的合唱比赛,每队均由20名队员组成.其中两队队员的平均身高为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> ,身高的方差分别为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> .如果单从队员的身高考虑,你认为演出形象效果较好的队是________.(填“甲队”或“乙队”)

13.如图,点ABC <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 上, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> ,则 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> ________度.
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>

14.如图,圆锥的母线长 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> ,底面圆的直径 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> ,则该圆锥的侧面积等于________ <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> .(结果用含 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 的式子表示)
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>

15.科技小组为了验证某电路的电压UV)、电流IA)、电阻 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 三者之间的关系: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> ,测得数据如下:

 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>

100

200

220

400

 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>

2.2

1.1

1

0.55


那么,当电阻 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 时,电流 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> ________A

16.如图.在 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 中, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> .以点A为圆心,以任意长为半径作弧交ABACDE两点;分别以点DE为圆心,以大于 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 长为半径作弧,在 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 内两弧相交于点P;作射线APBC于点F,过点F <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> ,垂足用G.若 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> ,则 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 的周长等于________cm
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>

评卷人

得分




三、解答题

17.计算: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>

18.先化简,再求值: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> ,其中 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>

19.如图,四边形ABCD是菱形,EF是对角线AC上的两点,且 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> ,连接BFFDDEEB
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
求证:四边形DEBF是菱形.

20.某校为落实“双减”工作,增强课后服务的吸引力,充分用好课后服务时间,为学有余力的学生拓展学习空间,成立了5个活动小组(每位学生只能参加一个活动小组):A.音乐;B.体育;C.美术;D.阅读;E.人工智能.为了解学生对以上活动的参与情况,随机抽取部分学生进行了调查统计,并根据统计结果,绘制了如图所示的两幅不完整的统计图.
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
根据图中信息,解答下列问题:
(1)①
此次调查一共随机抽取了________名学生;
补全条形统计图(要求在条形图上方注明人数);
扇形统计图中圆心角 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> ________度;
(2)
若该校有3200名学生,估计该校参加D组(阅读)的学生人数;
(3)
刘老师计划从E组(人工智能)的甲、乙、丙、丁四位学生中随机抽取两人参加市青少年机器人竞赛,请用树状图法或列表法求出恰好抽中甲、乙两人的概率.

21.如图是某水库大坝的横截面,坝高 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> ,背水坡BC的坡度为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> .为了对水库大坝进行升级加固,降低背水坡的倾斜程度,设计人员准备把背水坡的坡度改为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> ,求背水坡新起点A与原起点B之间的距离.(参考数据: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> .结果精确到0.1m
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>

22.为响应乡村振兴号召,在外地创业成功的大学毕业生小姣毅然返乡当起了新农人,创办了果蔬生态种植基地.最近,为给基地蔬菜施肥,她准备购买甲、乙两种有机肥.已知甲种有机肥每吨的价格比乙种有机肥每吨的价格多100元,购买2吨甲种有机肥和1吨乙种有机肥共需1700元.
(1)
甲、乙两种有机肥每吨各多少元?
(2)
若小姣准备购买甲、乙两种有机肥共10吨,且总费用不能超过5600元,则小姣最多能购买甲种有机肥多少吨?

23.如图,在 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 中, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> .以AB为直径的 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 与线段BC交于点D,过点D <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> ,垂足为EED的延长线与AB的延长线交于点P
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
(1)
求证:直线PE <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 的切线;
(2)
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 的半径为6 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> ,求CE的长.

24.如图1,在 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 中, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> .点DA点出发,沿线段AB向终点B运动.过点DAB的垂线,与 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 的直角边AC(或BC)相交于点E.设线段AD的长为acm),线段DE的长为hcm).
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
(1)
为了探究变量ah之间的关系,对点D在运动过程中不同时刻ADDE的长度进行测量,得出以下几组数据:

变量acm

0

0.5

1

1.5

2

2.5

3

3.5

4

变量hcm

0

0.5

1

1.5

2

1.5

1

0.5

0


在平面直角坐标系中,以变量a的值为横坐标,变量h的值为纵坐标,描点如图2-1;以变量h的值为横坐标,变量a的值为纵坐标,描点如图2-2
根据探究的结果,解答下列问题:
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 时, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> ________;当 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 时, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> ________
将图2-1,图2-2中描出的点顺次连接起来.
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
下列说法正确的是________.(填“A”或“B”
A
.变量h是以a为自变量的函数        B.变量a是以h为自变量的函数
(2)
如图3,记线段DE <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 的一直角边、斜边围成的三角形(即阴影部分)的面积 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> s
分别求出当 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 时,s关于a的函数表达式;
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 时,求a的值.
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>

25.如图1,在矩形ABCD中, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> .点E是线段AD上的动点(点E不与点AD重合),连接CE,过点E <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> ,交AB于点F
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
(1)
求证: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
(2)
如图2,连接CF,过点B <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> ,垂足为G,连接AG.点M是线段BC的中点,连接GM
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 的最小值;
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 取最小值时,求线段DE的长.

26.已知抛物线 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> x轴相交于点 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> ,与y轴相交于点C
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
(1)
求抛物线的表达式;
(2)
如图1,将直线BC间上平移,得到过原点O的直线MN.点D是直线MN上任意一点.
当点D在抛物线的对称轴l上时,连接CD,关x轴相交于点E,水线段OE的长;
如图2,在抛物线的对称轴l上是否存在点F,使得以BCDF为顶点的四边形是平行四边形?若存在,求出点F与点D的坐标;若不存在,请说明理由.

参考答案

1.A

【解析】
根据绝对值的含义求出各个数的绝对值,再比较大小即可.
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 0的绝对值为0 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
绝对值最大的数为-2
故选:A

2.B

【解析】
根据轴对称图形和中心对称图形的定义判断即可.
解:A、该图形是轴对称图形,不是中心对称图形,故A选项错误;
B
、该图形既是轴对称图形,也是中心对称图形,故B选项正确;
C
、该图形不是轴对称图形,是中心对称图形,故C选项错误;
D
、该图形既不是轴对称图形,也不是中心对称图形,故D选项错误.
故答案为B

3.D

【解析】
根据合并同类项、同底数幂的除法法则,完全平方公式以及二次根式的计算法则进行计算即可.
A.
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 不能合并,故A错误;
B.
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> ,故B错误;
C.
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> ,故C错误;
D.
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> ,故D正确;
故答案为:D

4.A

【解析】
根据 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 即可判断.
解: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 一元二次方程 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 有两个不相等的实数根.
故选:A

5.C

【解析】
现将数列从小达到重新排列,再根据中位数和众数的定义求解即可.
数列从小达到重新排列如下:
85
889092939395
中位数为:92,众数为:93
故选:C

6.D

【解析】
由抛物线的表达式和函数的性质逐一求解即可.
解:对于y=x-12+5
a=10,故抛物线开口向上,故A错误;
顶点坐标为(15),故B错误;
该函数有最小值,是小值是5,故C错误;
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 时,yx的增大而增大,故D正确,
故选:D

7.C

【解析】
利用平行线的判定条件进行分析即可得出结果.
解:A、当 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 时, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> ;故A不符合题意;
B
、当 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 时, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> ;故B不符合题意;
C
、当 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 时, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> ;故C符合题意;
D
、∵ <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> ,则 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> ,则 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> ;故D不符合题意;
故选:C

8.B

【解析】
ADx轴,BCx轴,由 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 即可求解;
解:如图,作ADx轴,BCx轴,
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
故选:B

9. <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>

【解析】
根据二次根式成立的条件可直接进行求解.
解:由题意得:
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> ,解得: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
故答案为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>

10. <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>

【解析】
由分式的运算法则进行计算,即可得到答案.
解: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
故答案为: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>

11.-3-2

【解析】
P(32) 关于x轴对称的点 P′ 的坐标是(-3-2),
故答案是:(-3-2).

12.乙队

【解析】
根据方差的定义,方差越小数据越稳定,即可得出答案.
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
应该选乙队参赛;
故答案为:乙队

13.31

【解析】
根据圆周角定理进行求解即可;
解:由圆周角定理可知: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
故答案为:31

14. <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>

【解析】
根据圆锥的侧面积=底面周长×母线长÷2,即可求出答案.
解:根据题意,
圆锥的母线长 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> ,底面圆的直径 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
圆锥的侧面积为:
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
故答案为: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>

15.4

【解析】
由表格数据得到定值 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> V,代入电阻值即可求解;
解:∵ <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> V
当电阻 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 时, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> A
故答案为:4

16.8

【解析】
由角平分线的性质,得到 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> ,然后求出 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 的周长即可.
解:根据题意,
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 中, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
由角平分线的性质,得 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 的周长为:
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
故答案为:8

17.3

【解析】
根据特殊角的三角函数值、绝对值的意义和负整数指数幂的计算方法计算即可.
解:原式 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
=3

18.ab4

【解析】
把分母分解为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> ,利用通分进行括号里分式的计算,再用分式的除法法则进行计算,最后代入求值;
解:原式 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 时,原式 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>

19.见解析

【解析】
先证明四边形DEBF是平行四边形,再结合 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 可得结论.
连接BD,交AC于点O
四边形ABCD是茥形,
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
又∵ <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> ,即 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
四边形DEBF是平行四边形.
又∵ <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> ,即 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
四边形DEBF是菱形.
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>

20.(1)①200;②见解析;③54
(2)1120
(3)
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>

【解析】
1)①由 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 组的人数及其所占百分比可得样本容量;②由总人数减去除 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 组的人数即可得到 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 组的人数;③ <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 乘以 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 人数所占比例即可;
2 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 乘以 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 人数所占比例即可;
3)根据题意列出树状图即可求解
(1)
解:(1)① <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 组人数 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
补全的条形统计图如图所示:
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
(2)
解: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
(3)
解:画树状图如下:
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
从甲、乙、丙、四位学生中随机抽取两人共有12种等可能性的结果,恰好抽中甲、乙两人的所有等可能性结果有2种,
因此, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> (恰好抽中甲、乙两人) <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>

21.背水坡新起点A与原起点B之间的距离约为14.6m

【解析】
通过解直角三角形 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> ,分别求出ADBD的长,由 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 求出AB的长.
解:在 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 中,∵背水坡BC的坡度 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 中,∵背水坡AC的坡度 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
答:背水坡新起点A与原起点B之间的距离约为14.6m

22.(1)甲种有机肥每吨600元,乙种有机肥每吨500
(2)
小妏最多能购买甲种有机用6

【解析】
1)设甲种有机肥每吨x元,乙种有机肥每吨y元,根据甲种有机肥每吨的价格比乙种有机肥每吨的价格多100元,购买2吨甲种有机肥和1吨乙种有机肥共需1700元列出二元一次方程组求解即可;
2)设沟买甲种有机肥m呠,则购实乙种有机肥 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 吨,根据总费用不能超过5600元列不等式求解即可.
(1)
设甲种有机肥每吨x元,乙种有机肥每吨y元,
根据题意,得 解得
答:甲种有机肥每吨600元,乙种有机肥每吨500元.
(2)
设沟买甲种有机肥m呠,则购实乙种有机肥 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 吨,
根据题意,得 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> ,解得 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
答:小姣最多能购买甲种有机用6吨.

23.(1)见解析
(2)3

【解析】
1)连接ADOD,根据等腰三角形的性质可证得 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> ,根据平行线的判定与性质可证得 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> ,然后根据切线的判定即可证得结论;
2)根据含30°角的直角三角形的性质求得CDCE   即可.
(1)
证明:连接ADOD,记 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
又∵OD是⊙O的半径,
直线PE是⊙O的切线.
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
(2)
连接AD
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
AB是直径,
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
又∵ <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
又∵ <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 为等边三角形,
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 中,∵ <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>

24.(1)①1.513;②见解析;③A
(2)①
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 时, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> ;当 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 时, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> ;② <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>

【解析】
1)①根据题意,对照变量h和变量a对应的数值即可填写,②图2-1,图2-2中描出的点顺次连接起来即可;③根据函数的定义即可判断;
2) ①如图,当 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 时, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> ,得到阴影部分是三角形ADE的面积: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> ;当 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 时, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> ,得到阴影部分的面积是三角形BDE的面积: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> .②当 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 时,令 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> ,解得a;当 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 时,令 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> ,解得a即可求解;
(1)
解:①根据题意,对照变量h和变量a对应的数值,当 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 时, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 1.5;当 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 时, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 13
故答案为:1.513
连线如图2-1、图2-2所示:
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
根据函数的定义:设在某变化过程中有两个变量xy,如果对于x在某一范围
内的每一个确定的值,y都有唯一确定的值与它对应,那么就称yx的函数,x
做自变量,所以变是h是以a为自变量的函数,故A选项符合,
故选:A.
(2)
如图3,当 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 时, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
阴影部分的面积: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 时, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
阴影部分的面积: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 时, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> ;当 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 时, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 时,令 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> ,解得 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> (不符合题意,舍去).
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 时,令 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> ,解得 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> (不符合题意,含去).
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 时, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>

25.(1)见解析
(2)①5
;② <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>

【解析】
1)证明出 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 即可求解;
2)①连接AM.先证明 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> .确定出点G在以点M为圆心,3为半径的圆上.当AGM三点共线时, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> .此时, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 取最小值.在 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 中利用勾股定理即可求出AM,则问题得解.②先求出AF,求AF的第一种方法:过点M <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> FC于点N,即有 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> ,进而有 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> .设 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> ,则 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> .再根据 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> ,得到 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> ,得到 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> ,则有 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> ,解方程即可求出AF;求AF的第二种方法:过点G <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> BC于点H.即有 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> .则有 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> ,根据 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> ,可得 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> ,进而求出 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> .由 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> ,即可求出AF.求出AF之后,由(1)的结论可得 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> .设 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> ,则 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> ,即有 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> ,解得解方程即可求出DE
(1)
证明:如图1
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
四边形ABCD是矩形,
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
(2)
解:如图2-1,连接AM
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 是直角二角形.
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
G在以点M为圆心,3为半径的圆上.
AGM三点不共线时,由三角形两边之和大于箒三边得: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
AGM三点共线时, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
此时, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 取最小值.在 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 中, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 的最小值为5
(求AF的方法一)如图2-2,过点M <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> FC于点N
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> ,则 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
由①知 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 的最小值为5、即 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
又∵ <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> ,解得 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> ,即 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
(求AF的方法二)
如图2-3,过点G <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> BC于点H
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
由①知 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 的最小值为5,即 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
又∵ <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> ,即 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
解得 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
由(1)的结论可得 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> ,则 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
解得 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>

26.(1) <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
(2)①
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> ;②在点F,使得以BCDF为顶点的四边形是平行四边形.当点F的坐标为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 时,点D的坐标: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> ;当点F的坐标为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 时,点D的坐标: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>

【解析】
(1)
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 代入 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 即可得出抛物线的表达式;
2)①求出直线BC解析式: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> ,再由直线MN <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 及抛物线的对称轴: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> ,即可得出 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> .进而得出直线CD的解析式为: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> ,即可得出答案;
分以BC为边时,即 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> ,以及分以BC为对角线时,进行讨论即可得出答案 .
(1)
解:将点 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 代入 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 得:
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
解得 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
抛物线的表达式为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
(2)
由(1)可知: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
设直线BC <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> ,将点 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 代入得:
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
解得 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
直线BC <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> ,则直线MN <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
抛物线的对称轴: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 代入 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> ,得 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
设直线CD <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> ,将点 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 代入得:
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
解得 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
直线CD <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 时,得 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
存在点F,使得以BCDF为项点的四边形是平行四边形.
理由如下:
I)若平行四边形以BC为边时,由 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 可知,FD在直线MN上,
F是直线MN与对称轴l的交点,即 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
由点D在直线MN上,设 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
如图2-1,若四边形BCFD是平行四边形,则 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
过点Dy轴的垂线交对称轴l于点G,则 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 轴,
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
又∵ <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>    
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> ,解得 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
如图2-2,若四边形BCDF是平行四边形,则 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
同理可证: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> ,解得 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
II)若平行四边形以BC为对角线时,由于点DBC的上方,则点F一定在BC的下方.
如图2-3,存在一种平行四边形,即 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> ,同理可证: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
解得 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
综上所述,存在点F,使得以BCDF为顶点的四边形是平行四边形.
当点F的坐标为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 时,点D的坐标: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>
当点F的坐标为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a> 时,点D的坐标: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/982/" title="湖南省" class="c1" target="_blank">湖南省</a> <a href="/tags/1036/" title="郴州" class="c1" target="_blank">郴州</a> <a href="/tags/1121/" title="湖南" class="c1" target="_blank">湖南</a>