名校
1 . 如图,在四棱锥
中,底面
为梯形,平面
平面![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5528310855c85b21a7b627208f551b2c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d52623aef17583cfb3bbbe0f84e1979c.png)
为侧棱
的中点,且
.
![](https://img.xkw.com/dksih/QBM/2018/1/18/1863277310517248/1864621339992064/STEM/879d41eecadc4db5aa97975df2fef02a.png?resizew=134)
(1)证明:
平面
;
(2)求二面角
的余弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0585b6c0f156eecf9662b9846d4eb693.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/93edc7bb513f40a89173121c8570cd65.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5528310855c85b21a7b627208f551b2c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d52623aef17583cfb3bbbe0f84e1979c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/827d63fc436eac20adaf279d57b0ea1a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e0629ce42392a7fe9be21d25c39c3e64.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/058953fc3ed0af5ddd0a44ef687f2c8d.png)
![](https://img.xkw.com/dksih/QBM/2018/1/18/1863277310517248/1864621339992064/STEM/879d41eecadc4db5aa97975df2fef02a.png?resizew=134)
(1)证明:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/932a04304f2d4975955d4baabb2deeea.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1e582d73b96ba649378379c3074d506d.png)
(2)求二面角
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b33b7213d99a817bff19bcf740a0697c.png)
您最近一年使用:0次
2018-01-20更新
|
765次组卷
|
4卷引用:河南省郑州市商丘市名师联盟 2020-2021学年高三11月质量检测巩固卷数学(理科)试题
名校
2 . 如图,四边形
和四边形
均是直角梯形,
二面角
是直二面角,
.
(1)证明:在平面
上,一定存在过点
的直线
与直线
平行;
(2)求二面角
的余弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2dde327febef2331a4766a79b433cc02.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2b8e554925cc139260dd5c289805068a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0ed12dbce4429a93b12a2aaad0da5520.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a31a38de26ae485ae43f55feada1b226.png)
(1)证明:在平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/500df0e782bb081e608f4bc1d576afcf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0f85fca60a11e1af2bf50138d0e3fe62.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d004d2d115b477ade6af7ddb93db0df8.png)
(2)求二面角
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/99d65b5127ccd01345f8bca5d8a94bc4.png)
![](https://img.xkw.com/dksih/QBM/2017/11/14/1817093975367680/1818574724825088/STEM/dd1a78c8f7c242628fdfc7bd7aa8a62c.png?resizew=136)
您最近一年使用:0次