题目
题型:不详难度:来源:
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022041455-95386.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022041455-63616.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022041456-96950.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022041456-55210.png)
A.![]() | B.![]() | C.![]() | D.![]() |
答案
解析
试题分析:因为
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022041457-47904.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022041457-82113.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022041456-96950.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022041457-38941.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022041458-31765.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022041458-36035.png)
求线面角关键找垂线,找出垂线就能在直角三角形中研究线面角大小.另外需熟悉正方体中面对角线与体对角线量的关系.
核心考点
举一反三
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022041445-43697.png)
A.![]() | B.![]() | C.![]() | D.![]() |
①已知平面
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022041431-28398.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022041431-33419.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022041432-36367.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022041432-46806.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022041432-94989.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022041432-45803.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022041433-59984.png)
②
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022041433-14161.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022041433-14355.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022041433-85055.png)
③三棱锥的四个面可以都是直角三角形。
④平面
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022041431-28398.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022041431-33419.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022041433-32436.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022041434-26577.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022041431-33419.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022041434-69490.png)
⑤三棱锥中若有两组对棱互相垂直,则第三组对棱也一定互相垂直;
其中正确的命题编号是 (写出所有正确命题的编号)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022041418-69807.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022041418-65007.png)
(Ⅰ)求三棱锥E-PAD的体积;
(Ⅱ)当点E为BC的中点时,试判断EF与平面PAC的位置关系,并说明理由;
(Ⅲ)证明:无论点E在边BC的何处,都有PE⊥AF
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022041405-84208.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022041405-99816.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022041405-48574.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022041405-74209.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022041405-48574.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022041406-65310.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022041406-92294.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022041406-99095.png)
(Ⅰ)求证:
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022041406-51831.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022041406-90392.png)
(Ⅱ)求证:平面
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022041407-17122.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022041407-22328.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022041407-69473.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022041353-98770.png)
(1)求证:平面MAP⊥平面SAC。
(2)求二面角M—AC—B的平面角的正切值;
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