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【327746】2022年山东省东营市中考数学真题

时间:2025-01-20 20:10:41 作者: 字数:21957字
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2022年山东省东营市中考数学真题

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得分





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得分




一、选择题

1.-2的绝对值是(     
A
2
B
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
C
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
D
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>

2.下列运算结果正确的是(       
A
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
B
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
C
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
D
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>

3.如图,直线 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> ,一个三角板的直角顶点在直线a上,两直角边均与直线b相交, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> ,则 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>        
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
A
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
B
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
C
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
D
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>

4.植树节当天,七年级1班植树300棵,正好占这批树苗总数的 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> ,七年级2班植树棵数是这批树苗总数的 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> ,则七年级2班植树的棵数是(       
A
36
B
60
C
100
D
180

5.一元二次方程 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 的解是(       
A
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
B
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
C
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
D
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>

6.如图,任意将图中的某一白色方块涂黑后,能使所有黑色方块构成的图形是轴对称图形的概率是(       
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
A
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
B
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
C
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
D
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>

7.如图,点D <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 上任一点, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 于点E,连接 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 相交于点F,则下列等式中不成立的是(       
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
A
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
B
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
C
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
D
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>

8.如图,一次函数 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 与反比例函数 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 的图象相交于AB两点,点A的横坐标为2,点B的横坐标为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> ,则不等式 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 的解集是(       
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
A
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
B
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
C
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
D
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>

9.用一张半圆形铁皮,围成一个底面半径为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 的圆锥形工件的侧面(接缝忽略不计),则圆锥的母线长为(       
A
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
B
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
C
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
D
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>

10.如图,已知菱形 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 的边长为2,对角线 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 相交于点O,点MN分别是边 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 上的动点, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> ,连接 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> .以下四个结论正确的是(       
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 是等边三角形;② <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 的最小值是 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> ;③当 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 最小时 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> ;④当 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 时, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> .
A
.①②③
B
.①②④
C
.①③④
D
.①②③④

评卷人

得分




二、填空题

11.2022220日,北京冬奥会圆满落幕,赛事获得了数十亿次数字平台互动,在中国仅电视收视人数就超6亿.6亿用科学记数法表示为____________.

12.因式分解x39x=__________

13.为了落实“双减”政策,东营市某学校对初中学生的课外作业时长进行了问卷调查,15名同学的作业时长统计如下表,则这组数据的众数是____________分钟.

作业时长(单位:分钟)

50

60

70

80

90

人数(单位:人)

1

4

6

2

2



14.如图,在 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 中,弦 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 半径 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> ,则 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 的度数为____________
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>

15.关于x的一元二次方程 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 有两个不相等的实数根,则k的取值范围是____________

16.如图, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 是等腰直角三角形,直角顶点与坐标原点重合,若点B在反比例函数 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 的图象上,则经过点A的反比例函数表达式为____________
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>

17.如图,在 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 中,点FG <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 上,点EH分别在 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 上,四边形 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 是矩形, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 的高. <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> ,那么 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 的长为____________
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>

18.如图, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 是等边三角形,直线 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 经过它们的顶点 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> ,点 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> x轴上,则点 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 的横坐标是____________.
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>

评卷人

得分




三、解答题

19.计算及先化简,再求值:
(1)
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
(2)
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> ,其中 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> .

20.中国共产党的助手和后备军——中国共青团,担负着为中国特色社会主义事业培养合格建设者和可靠接班人的根本任务.成立一百周年之际,各中学持续开展了A:青年大学习;B:背年学党史;C:中国梦宣传教育;D:社会主义核心价值观培育践行等一系列活动,学生可以任选一项参加.为了解参与情况,进行了一次抽样调查,根据收集的数据绘制了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/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
请根据图中提供的信息,解答下列问题:
(1)
在这次调查中,一共抽取了____________名学生;
(2)
补全条形统计图;
(3)
若该校共有学生1280名,请估计参加B项活动的学生数;
(4)
小杰和小慧参加了上述活动,请用列表或画树状图的方法,求他们参加同一项活动的概率.

21.如图, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 的直径,点C <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 上一点, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 于点D <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 平分 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
(1)
求证:直线 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 的切线;
(2)
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 的半径为2,求图中阴影部分的面积.

22.胜利黄河大桥犹如一架巨大的竖琴,凌驾于滔滔黄河之上,使黄河南北“天堑变通途”.已知主塔 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 垂直于桥面 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 于点B,其中两条斜拉索 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 与桥面 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 的夹角分别为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> ,两固定点DC之间的距离约为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> ,求主塔 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 的高度(结果保留整数,参考数据: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>

23.为满足顾客的购物需求,某水果店计划购进甲、乙两种水果进行销售.经了解,甲水果的进价比乙水果的进价低20%,水果店用1000元购进甲种水果比用1200元购进乙种水果的重量多10千克,已知甲,乙两种水果的售价分别为6/千克和8/千克.
(1)
求甲、乙两种水果的进价分别是多少?
(2)
若水果店购进这两种水果共150千克,其中甲种水果的重量不低于乙种水果重量的2倍,则水果店应如何进货才能获得最大利润,最大利润是多少?

24.如图,抛物线 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> x轴交于点 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> ,点 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> ,与y轴交于点C
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
(1)
求抛物线的表达式;
(2)
在对称轴上找一点Q,使 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 的周长最小,求点Q的坐标;
(3)
P是抛物线对称轴上的一点,点M是对称轴左侧抛物线上的一点,当 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 是以 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 为腰的等腰直角三角形时,请直接写出所有点M的坐标.

25. <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 均为等边三角形,点ED分别从点AB同时出发,以相同的速度沿 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 运动,运动到点BC停止.
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
(1)
如图1,当点ED分别与点AB重合时,请判断:线段 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 的数量关系是____________,位置关系是____________
(2)
如图2,当点ED不与点AB重合时,(1)中的结论是否依然成立?若成立,请给予证明;若不成立,请说明理由;
(3)
当点D运动到什么位置时,四边形 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 的面积是 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 面积的一半,请直接写出答案;此时,四边形 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 是哪种特殊四边形?请在备用图中画出图形并给予证明.

参考答案

1.A

【解析】
根据数轴上某个数与原点的距离叫做这个数的绝对值的定义进行求解即可.
解:在数轴上,点-2到原点的距离是2,所以-2的绝对值是2
故选:A

2.D

【解析】
根据合并同类项,完全平方公式,同底数幂除法和算术平方根的运算法则逐一进行判断即可.
解:A.  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> ,原计算错误,不合题意;
B.
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> ,原计算错误,不合题意;
C.
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> ,原计算错误,不合题意;
D.
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> ,原计算正确,符合题意;
故选:D

3.B

【解析】
先根据平角的定义求出∠3的度数,再根据平行线的性质即可求出∠2的度数.
解:由题意得∠ABC=90°
∵∠1=40°

∴∠3=180°-∠1-∠
ABC=50°
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
∴∠2=∠3=50°

故选B
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>

4.C

【解析】
设这批树苗一共有x棵,根据七年级1班植树300棵,正好占这批树苗总数的 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> ,列出方程求解即可.
解:设这批树苗一共有x棵,
由题意得: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
解得 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
七年级2班植树的棵数是 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 棵,
故选C

5.D

【解析】
利用配方法解方程即可.
解:∵ <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
解得 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
故选D

6.A

【解析】
根据轴对称图形的定义,结合概率计算公式求解即可.
解:如图所示,由轴对称图形的定义可知当选取编号为1356其中一个白色区域涂黑后,能使黑色方块构成的图形是轴对称图形,
任意将图中的某一白色方块涂黑后,能使所有黑色方块构成的图形是轴对称图形的概率是 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
故选A
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>

7.C

【解析】
根据平行线分线段成比例定理即可判断A,根据相似三角形的性质即可判断BCD
解:∵ <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> ,△DEF∽△CBF,△ADE∽△ABC,故A不符合题意;
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> ,故B不符合题意,C符合题意;
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> ,故D不符合题意;
故选C

8.A

【解析】
根据不等式 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 的解集即为一次函数图象在反比例函数图象下方时自变量的取值范围进行求解即可.
解:由题意得不等式 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 的解集即为一次函数图象在反比例函数图象下方时自变量的取值范围,
不等式 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 的解集为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
故选A

9.B

【解析】
设圆锥的母线长为l,根据圆锥的底面圆周长为半圆形铁皮的周长(不包括直径)列式求解即可.
解:设圆锥的母线长为l
由题意得: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
故选B

10.D

【解析】
依据题意,利用菱形的性质及等边三角形的判定与性质,证出 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> ,然后证 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> AM=AN,即可证出.
MN最小值时,即AM为最小值,当 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 时,AM值最小,利用勾股定理求出 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> ,即可得到MN的值.
MN最小时,点MN分别为BCCD中点,利用三角形中位线定理得到 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> ,用勾股定理求出 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> ,而菱形ABCD的面积为: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> ,即可得到答案.
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 时,可证 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> ,利用相似三角形对应边成比例可得 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> ,根据等量代换,最后得到答案.
解:如图:在菱形ABCD中,AB=BC=AD=CD <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> OA=OC
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 为等边三角形,
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
AM=AN
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 为等边三角形,
故①正确;
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
MN最小值时,即AM为最小值,当 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 时,AM值最小,
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
故②正确;
MN最小时,点MN分别为BCCD中点,
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 中,
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
而菱形ABCD的面积为: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
故③正确,
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 时,
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
故④正确;
故选:D
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>

11. <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>

【解析】
科学记数法的表示形式为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 的形式,其中1≤|a|10n为整数.确定n的值时,要看把原数变成a时,小数点移动了多少位,n的绝对值与小数点移动的位数相同.当原数绝对值≥10时,n是正整数;当原数的绝对值<1时,n是负整数.
解:6亿= <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
故答案为: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>

12.xx+3)(x3

【解析】
先提取公因式x,再利用平方差公式进行分解.
解:x39x
=
xx29),
=
xx+3)(x3).

13.70

【解析】
根据众数的定义,人数最多的即为这组数据的众数.
解:由表可知:
∵6
4221
这组数据的众数是70分钟.
故答案为:70

14.100°##100

【解析】
先根据平行线的性质求出∠OCA的度数,再根据等边对等角求出∠OAC的度数,即可利用三角形内角和定理求出∠AOC的度数.
解:∵ <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
∴∠
OCA=∠BOC=40°
OA=OC
∴∠
OAC=∠OCA=40°
∴∠
AOC=180°-∠OAC-∠OCA=100°
故答案为:100°

15. <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>

【解析】
根据一元二次方程二次项系数不为0,以及根的判别式即可得出k的取值范围.
解:∵关于x的一元二次方程 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 有两个不相等的实数根,
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
故答案为: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>

16. <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>

【解析】
如图所示,过点AACx轴于C,过点BBDx轴于D,证明ACOODB得到AC=ODOC=BD,设点B的坐标为(ab),则点A的坐标为(-ba),再由点B在反比例函数 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> ,推出 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> ,由此即可得到答案.
解:如图所示,过点AACx轴于C,过点BBDx轴于D,则∠ACO=∠ODB=90°
由题意得OA=OB,∠AOB=90°
∴∠
CAO+∠COA=∠AOC+∠BOD=90°
∴∠
CAO=∠DOB
∴△
ACO≌△ODBAAS),
AC=ODOC=BD
设点B的坐标为(ab),则AC=OD=aOC=BD=b
A的坐标为(-ba),
B在反比例函数 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
经过点A的反比例函数表达式为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
故答案为: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>

17. <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> ##4.8

【解析】
通过四边形EFGH为矩形推出 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> ,因此△AEH与△ABC两个三角形相似,将AM视为△AEH的高,可得出 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> ,再将数据代入即可得出答案.
四边形EFGH是矩形,
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
AMAD分别是△AEH和△ABC的高,
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
代入可得: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
解得 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
故答案为: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>

18. <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>

【解析】
如图,设直线 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> x轴交于点C,求出点AC的坐标,可得OA2OC <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> ,然后解直角三角形求出∠ACO30°,可得 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> ,然后求出 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> ,…,进而可得 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> ,再求出 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 即可.
解:如图,设直线 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> x轴交于点C
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 中,当x0时,y2
y0时,即 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> ,解得: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
A02),C <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 0),
OA2OC <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
∴tan∠
ACO <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
∴∠
ACO30°
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 是等边三角形,
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
AC <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
AO <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
同理可得: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> ,…,
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 的横坐标是 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
故答案为: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>

19.(1)3
(2)
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 5

【解析】
1)先根据特殊角的三角函数值计算,再根据二次根式的混合运算的法则进行计算即可.
2)根据分式的加法和除法可以化简题目中的式子,然后将xy的值代入化简后的式子即可解答本题.
1
原式= <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
=
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
=3
2
原式= <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
=
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
=
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
x=3y=2时,原式= <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> =5

20.(1)200
(2)
见解析;
(3)
估计参加B项活动的学生数有512名;
(4)
画树状图见解析,他们参加同一项活动的概率为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>

【解析】
1)根据D项活动所占圆心角度数和D项活动的人数计算即可;
2)根据总人数求出参加C项活动的人数,进而可补全条形统计图;
3)用该校总学生人数乘以抽查的学生中参加B项活动所占的比例即可;
4)画出树状图可知,共有16种等可能的结果,其中他们参加同一项活动的情况数有4种,然后根据概率公式计算即可.
1
解: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> (名),
即在这次调查中,一共抽取了200名学生,
故答案为:200
2
参加C项活动的人数为:20020804060(名),
补全条形统计图如图:
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
3
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> (名),
答:估计参加B项活动的学生数有512名;
4
画树状图如图:
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
由树状图可知,共有16种等可能的结果,其中他们参加同一项活动的情况数有4种,
所以他们参加同一项活动的概率为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>

21.(1)见解析
(2)
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>

【解析】
1)连接OC,根据OB=OC,以及 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 平分 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 推导出 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> ,即可得出 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> ,从而推出 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> ,即证明得出结论;
2)过点O <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> F,利用 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 即可得出答案.
1
证明:连接OC,如图,
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 平分 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 于点D
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
直线 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 的切线;
2
过点O <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> F,如图,
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>

22.主塔 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 的高度约为78m

【解析】
RtABD中,利用正切的定义求出 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> ,然后根据∠C45°得出ABBC,列方程求出BD,即可解决问题.
解:∵ABBC
∴∠
ABC90°
RtABD中, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
RtABC中,∠C45°
ABBC
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> m
ABBC <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> m
答:主塔 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 的高度约为78m

23.(1)甲种水果的进价是4/千克,乙种水果的进价是5/千克;
(2)
水果店购进甲种水果100千克,乙种水果50千克时获得最大利润,最大利润是350元.

【解析】
1)设乙种水果的进价是x/千克,根据“甲水果的进价比乙水果的进价低20%,水果店用1000元购进甲种水果比用1200元购进乙种水果的重量多10千克”列出分式方程,解方程检验后可得出答案;
2)设水果店购进甲种水果a千克,获得的利润为y元,则购进乙种水果(150a)千克,根据利润=(售价-进价)×数量列出y关于a的一次函数解析式,求出a的取值范围,然后利用一次函数的性质解答.
1
解:设乙种水果的进价是x/千克,
由题意得: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
解得: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
经检验, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 是分式方程的解且符合题意,
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
答:甲种水果的进价是4/千克,乙种水果的进价是5/千克;
2
解:设水果店购进甲种水果a千克,获得的利润为y元,则购进乙种水果(150a)千克,
由题意得: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
10
ya的增大而减小,
甲种水果的重量不低于乙种水果重量的2倍,
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
解得: <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 时,y取最大值,此时 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
答:水果店购进甲种水果100千克,乙种水果50千克时获得最大利润,最大利润是350元.

24.(1) <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
(2)
1-2
(3)
-10)或( <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> -2)或( <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 2

【解析】
1)利用待定系数法求解即可;
2)先求出点C的坐标和抛物线的对称轴,如图所示,作点C关于直线 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 的对称点E,连接AEEQ,则点E的坐标为(2-3),根据轴对称最短路径可知AE与抛物线对称轴的交点即为点Q
3)分两种情况当∠BPM=90°和当∠PBM=90°两种情况讨论求解即可.
1
解:∵抛物线 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> x轴交于点 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> ,点 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
抛物线解析式为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
2
解:∵抛物线解析式为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> ,与y轴交于点C
抛物线对称轴为直线 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> ,点C的坐标为(0-3
如图所示,作点C关于直线 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 的对称点E,连接AEEQ,则点E的坐标为(2-3),   
由轴对称的性质可知CQ=EQ
∴△
ACQ的周长=AC+AQ+CQ
要使△ACQ的周长最小,则AQ+CQ最小,即AQ+QE最小,
AQE三点共线时,AQ+QE最小,
设直线AE的解析式为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
直线AE的解析式为 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 时, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
Q的坐标为(1-2);
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
3
解: 如图1所示,当点Px轴上方,∠BPM=90°时,过点P <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 轴,过点MMFEFF,过点BBEEFE
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
∵△
PBM是以PB为腰的等腰直角三角形,
PA=PB,∠MFP=∠PEB=∠BPM=90°
∴∠
FMP+∠FPM=∠FPM+∠EPB=90°
∴∠
FMP=∠EPB
∴△
FMP≌△EPBAAS),   
PE=MFBE=PF
设点P的坐标为(1m),
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
M的坐标为(1-mm-2),
M在抛物线 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 上,
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>    
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
解得 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> (舍去),
M的坐标为(-10);
同理当当点Px轴下方,∠BPM=90°时可以求得点M的坐标为(-10);
如图2所示,当点Px轴上方,∠PBM=90°时,过点B <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 轴,过点PPEEFE,过点MMFEFF,设点P的坐标为(1m),
同理可证△PEB≌△BFMAAS),
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
M的坐标为(3-m-2),
M在抛物线 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 上,
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
解得 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> (舍去),
M的坐标为( <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> -2);
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
如图3所示,当点Px轴下方,∠PBM=90°时,
同理可以求得点M的坐标为( <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 2);
综上所述,当△PMB是以PB为腰的等腰直角三角形时,点M的坐标为(-10)或( <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> -2)或( <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 2).
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>

25.(1)CD=EFCDEF
(2)CD=EFCDEF,成立,理由见解析
(3)
D运动到BC的中点时, <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 是菱形,证明见解析

【解析】
1)根据 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 均为等边三角形,得到AF=ADAB=BC,∠FAD=∠ABC=60°,根据ED分别与点AB重合,得到AB=ADEF=AFCD=BC,∠FAD=∠FAB,推出CD=EFCDEF
2)连接BF,根据∠FAD=∠BAC=60°,推出∠FAB=∠DAC,根据AF=ADAB=AC,推出AFBADC,得到∠ABF=∠ACD=60°BF=CD,根据AE=BD,推出BE=CD,得到BF=BE,推出BFE是等边三角形,得到BF=EF,∠FEB=60°,推出CD=EFCDEF
3)过点EEGBC于点G,设ABC的边长为aAD=h,根据AB=BCBD=CD=  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> BC=  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> aBD=AE,推出AE=BE=  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> AB,根据AB=AC, 推出ADBC,得到EGAD,推出EBGABD,推出 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> ,得到 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> =  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> h,根据CD=EFCDEF,推出四边形CEFD是平行四边形,推出 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> ,根据EF=BDEFBD,推出四边形BDEF是平行四边形,根据BF=EF,推出 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 是菱形.
1
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 均为等边三角形,
AF=ADAB=BC,∠FAD=∠ABC=60°
当点ED分别与点AB重合时,AB=ADEF=AFCD=BC,∠FAD=∠FAB
CD=EFCDEF
故答案为:CD=EFCDEF
2
CD=EFCDEF,成立.
证明:
连接BF
∵∠
FAD=∠BAC=60°
∴∠
FAD-∠BAD=∠BAC-∠BAD
即∠FAB=∠DAC
AF=ADAB=AC
AFBADC(SAS)
∴∠
ABF=∠ACD=60°BF=CD
AE=BD
BE=CD
BF=BE
BFE是等边三角形,
BF=EF,∠FEB=60°
CD=EFBCEF
CDEF
CD=EFCDEF
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
3
如图,当点D运动到BC的中点时,四边形 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 的面积是 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 面积的一半,此时,四边形 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 是菱形.
证明:
过点EEGBC于点G,设ABC的边长为aAD=h
AB=BCBD=CD=  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> BC=  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> aBD=AE
AE=BE=  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> AB
AB=AC
ADBC
EGAD
EBGABD
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> =  <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> h
由(2)知,CD=EFCDEF
四边形CEFD是平行四边形,
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> ,
此时,EF=BDEFBD
四边形BDEF是平行四边形,
BF=EF
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a> 是菱形.
 <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/561/" title="山东" class="c1" target="_blank">山东</a> <a href="/tags/995/" title="山东省" class="c1" target="_blank">山东省</a> <a href="/tags/996/" title="东营" class="c1" target="_blank">东营</a>