题目
题型:不详难度:来源:
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022072541-36426.jpg)
(1)证明:A1B1⊥C1D;
(2)当
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022072541-38421.png)
答案
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022072541-60785.jpg)
又AC=BC,D为中点,所以CD⊥AB,则C1D⊥AB,
又A1B1//AB,所以A1B1⊥C1D ………………6分
(2)过A做AH⊥DE交ED的延长线于H,连接MH,
由MA⊥平面ABC,AH为MH在底面ABC内的射影,易得,
MH⊥DE,则∠MHA为二面角M—DE—A的平面角。 ………………10分
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022072541-19871.png)
法二:(1)以C为坐标原点建立空间直角坐标系C—xyz,则
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022072542-34875.png)
则
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022072542-33569.png)
(2)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022072542-10104.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022072542-24623.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022072543-90550.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022072543-35083.png)
解析
核心考点
试题【(本小题满分14分)在直三棱柱ABC—A1B1C1中,∠ACB=90°,AC=BC=AA1=1,D、E分别为棱AB、BC的中点,M为棱AA1上的点。 (1)证】;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/20191022/20191022072527-80671.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022072527-27744.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022072527-80149.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022072527-86428.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022072527-15795.png)
(1)求证:
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022072528-81831.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022072528-42202.png)
(2)求三棱锥
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022072528-64715.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022072528-24575.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022072511-64589.png)
(1)求证:AC⊥SD;
(2)若SD⊥平面PAC,求二面角P-AC-
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022072511-72031.png)
(3)在(2)的条件下,侧棱SC上是否存在一点E,使得BE∥平面PAC。若存在,求SE:EC的值;若不存在,试说明理由。
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022072511-12250.jpg)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022072456-32667.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022072457-37136.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022072457-62570.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022072457-81896.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022072457-18576.png)
和
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022072457-94504.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022072456-32667.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022072457-37136.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022072458-83182.png)
(1)试判断直线
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022072457-62570.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022072458-61899.png)
(2)求二面角
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022072458-89959.png)
(3)在线段
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022072457-94504.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022072459-37181.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022072459-99320.png)
![]() |
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022072440-22609.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022072440-87596.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022072440-80488.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022072441-31253.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022072441-31480.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022072440-22609.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022072441-97934.png)
(1)求证:
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022072441-95129.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022072441-31253.png)
(2)求二面角A-BF-C的平面角的余弦值;
(3)若点
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022072441-63902.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022072441-22093.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022072441-37147.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022072441-31384.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022072441-67287.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022072442-57530.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022072442-26369.jpg)
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