题目
题型:不详难度:来源:
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022062715-69882.png)
求AC和BD所成的角。(本题12分)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022062715-70422.png)
答案
解:取CD中点H,连结EH、HF
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022062716-14725.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022062716-68236.png)
同理:
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022062716-19397.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022062716-33761.png)
不防设
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022062716-28223.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022062717-29423.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022062716-33761.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022062717-26126.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022062716-33761.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022062717-52626.png)
解析
核心考点
举一反三
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022062709-26320.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022062709-88494.png)
A.![]() ![]() | B.![]() ![]() |
C.![]() ![]() | D.![]() ![]() |
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022062702-96057.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022062702-11728.png)
A.![]() | B.![]() | C.![]() | D.![]() |
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022062655-11383.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022062656-47724.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022062656-39407.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022062656-72903.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022062656-48053.png)
A.![]() | B.![]() | C.![]() | D.![]() |
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022062648-84392.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022062648-57389.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022062648-56581.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022062648-75658.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022062649-64488.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022062649-28276.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022062648-84392.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022062649-13943.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022062649-36741.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022062639-28818.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022062639-20060.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022062639-41960.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022062639-21337.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022062639-80015.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022062639-70547.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022062640-26499.png)
(Ⅰ)证明:
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022062640-87057.png)
(Ⅱ)求
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022062640-22402.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022062640-87810.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022062640-60633.png)
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