题目
题型:不详难度:来源:
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002932-42765.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002932-35181.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002932-12080.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002932-12080.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002932-55046.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002932-15647.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002932-37361.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002932-34994.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002932-51138.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002933-45100.png)
(Ⅰ)当
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002933-74524.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002933-85222.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002932-51138.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002933-45100.png)
(Ⅱ)在(Ⅰ)的条件下,求二面角
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002933-29193.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002933-63242.jpg)
答案
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002932-12080.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002933-80054.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002933-47859.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002933-53753.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002933-20297.jpg)
∴
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002933-41518.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002934-73957.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002934-30647.png)
∴
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002934-62057.png)
连接
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002934-81806.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002934-72826.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002934-14148.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002934-95698.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002934-50148.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002933-74524.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002933-85222.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002933-85222.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002934-52403.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002935-98757.png)
在
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002935-75137.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002935-34275.png)
即
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002935-10227.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002933-74524.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002933-85222.png)
(Ⅱ)方法一:在等腰直角
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002935-17902.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002933-45100.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002935-59456.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002936-12308.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002932-37361.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002936-62949.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002936-65104.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002936-39670.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002936-65104.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002936-87944.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002936-39670.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002936-16243.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002933-45100.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002936-74771.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002936-62468.png)
在平
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002936-91465.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002936-62468.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002935-59456.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002937-93964.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002937-25711.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002937-71519.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002937-41823.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002937-69464.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002937-81817.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002937-73342.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002937-43422.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002937-12464.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002938-35399.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002933-29193.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002938-25228.png)
在
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002938-75291.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002938-39547.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002938-20926.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002938-25439.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002938-81951.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002938-19684.png)
由
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002937-81817.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002938-90576.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002939-16226.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002939-19911.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002939-98479.png)
代入解得:
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002939-65683.png)
在
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002939-22219.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002939-61429.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002939-30788.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002939-51889.png)
∴二面角
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002933-29193.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002940-49373.png)
方法二:以
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002940-37031.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002940-26661.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002940-11842.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002936-16243.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002940-28497.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002940-20625.png)
设
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002940-27553.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002940-90017.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002941-52449.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002941-87018.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002941-71834.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002941-25791.png)
设
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002941-30440.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002933-85222.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002941-74299.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002941-51191.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002941-74299.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002941-45668.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002941-49591.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002942-80739.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002942-56595.png)
设
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002942-65030.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002936-62468.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002942-62690.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002942-66279.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002942-62690.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002942-55607.png)
又
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002943-68916.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002943-76190.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002943-54086.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002943-34600.png)
∴
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002944-88410.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002944-15516.png)
∴二面角
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002936-91465.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002933-29193.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002940-49373.png)
解析
核心考点
试题【如图,四棱锥中,⊥底面,底面为梯形,,,且,点是棱上的动点.(Ⅰ)当∥平面时,确定点在棱上的位置;(Ⅱ)在(Ⅰ)的条件下,求二面角的余弦值.】;主要考察你对空间几何体的结构特征等知识点的理解。[详细]
举一反三
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002915-74473.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002915-78093.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002915-78093.png)
A.1 | B.![]() | C.![]() | D.0 |
A.三角形 B.菱形但不是正方形
C.正方形 D.邻边不等的矩形
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002904-58355.png)
则在原正方体中,①AB与CD相交;②MN∥PQ;③AB∥PE;④MN与CD异面;⑤MN∥平面PQC.所给关系判断正确的是_____
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021002901-46350.jpg)
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