题目
题型:不详难度:来源:
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022060649-29175.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022060649-76626.png)
(I)求证:
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022060649-86007.png)
(II)求异面直线AB与CD所成角的余弦值;
(III)求点E到平面ACD的距离。
答案
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022060649-46989.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022060649-39283.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022060650-63216.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022060650-49321.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022060650-52186.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022060650-97590.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022060651-60033.png)
(II)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022060651-23162.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022060651-22241.png)
解析
试题分析:(I)证明:连结OC
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022060651-48895.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022060652-44360.png)
在
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022060652-68050.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022060652-30513.png)
而
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022060652-20590.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022060652-24321.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022060653-45597.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022060650-52186.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022060653-18375.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022060650-97590.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022060651-60033.png)
(II)解:取AC的中点M,连结OM、ME、OE,由E为BC的中点知
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022060653-35300.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022060650-49321.png)
在
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022060653-58046.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022060654-30500.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022060654-47379.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022060652-68050.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022060654-77445.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022060654-27434.png)
(III)解:设点E到平面ACD的距离为
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022060655-57723.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022060655-96295.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022060655-74257.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022060655-39886.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022060655-92825.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022060656-93433.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022060656-16513.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022060650-49321.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022060651-22241.png)
点评:本题还可用空间向量来证明计算
核心考点
试题【如图,四面体ABCD中,O、E分别是BD、BC的中点,(I)求证:平面BCD;(II)求异面直线AB与CD所成角的余弦值;(III)求点E到平面ACD的距离。】;主要考察你对线线角等知识点的理解。[详细]
举一反三
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022060643-48827.png)
(1)求证:平面
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022060643-97087.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022060643-83758.png)
(2)在底面A1D1上有一个靠近D1的四等分点H,求证: EH∥平面FGB1;
(3)求四面体EFGB1的体积.
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022060638-78359.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022060638-39939.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022060638-55954.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022060638-39939.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022060638-40484.png)
A.![]() ![]() | B.![]() ![]() |
C.![]() ![]() | D.![]() ![]() |
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022060631-47096.png)
A.
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022060631-14599.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022060631-95151.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022060631-27029.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022060631-48269.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022060622-97203.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022060622-97203.png)
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