题目
题型:不详难度:来源:
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022084610-15000.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022084610-89494.jpg)
答案
解:设棱长为a
取AC中点M链接EM.MF
因为M,E,F分别为AC,SC,AS中点
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022084610-25487.gif)
∠MEF是异面直线EF与SA所成的角其补角…………………………
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022084610-47883.gif)
连接SF
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022084611-89468.gif)
∠MEF=
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022084611-49187.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022084611-12542.gif)
解析
核心考点
举一反三
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022084558-84628.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022084558-82032.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022084558-50843.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022084559-97807.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022084559-47714.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022084559-65642.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022084559-74539.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022084559-46829.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022084600-37671.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022084559-46829.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022084600-73235.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022084600-23389.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022084559-47714.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022084600-49292.jpg)
(Ⅰ)当平面
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022084600-23389.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022084601-91524.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022084601-47107.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022084601-27307.gif)
(Ⅱ)当△
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022084600-23389.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022084559-47714.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022084601-91524.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022084601-96170.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022084601-27307.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022084552-62432.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022084552-99470.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022084552-84102.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022084552-85528.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022084552-44354.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022084553-22724.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022084553-32471.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022084553-86322.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022084553-82904.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022084554-94758.jpg)
(Ⅰ)求证:平面
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022084554-56798.gif)
(Ⅱ)求三棱锥
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022084554-21755.gif)
如图,在四棱锥
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022084523-35484.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022084523-20096.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022084523-58238.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022084523-71964.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022084524-30224.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022084524-63993.gif)
(I)证明
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022084524-24699.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022084524-71231.gif)
(II)证明
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022084524-57467.gif)
(III)求二面角
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022084525-38893.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022084518-38275.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022084518-57028.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022084518-56055.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022084518-71848.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022084512-66289.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022084512-56799.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022084512-45275.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022084513-51541.png)
运动,另一个端点
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022084513-24868.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022084513-64209.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022084512-56799.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022084513-37400.png)
围成的较小的几何体的体积为( )
A.![]() | B.![]() | C.![]() | D.![]() |
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