名校
1 . 如图,在梯形
中,
,
,
,现将
沿
翻折成直二面角
.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/5/381bc715-77fe-4609-938a-ada15fa13cc5.png?resizew=468)
(Ⅰ)证明:
;
(Ⅱ)若异面直线
与
所成角的余弦值为
,求二面角
余弦值的大小.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/68d31600cba2d5256c7e78b6122d6755.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6de3595bb7c79503fabd75d99196ccb9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d2c15801fee2405573677484f5dcfa4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cbced129627233661d88e9663a9e13c0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bf29d07c3751c41ab3503065a5a5052e.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/5/381bc715-77fe-4609-938a-ada15fa13cc5.png?resizew=468)
(Ⅰ)证明:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ec82279b14a119057fdd78b85d63e669.png)
(Ⅱ)若异面直线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/48f3c9abbd78e9a6840ee5f30381daac.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/56d266a04f3dc7483eddbc26c5e487db.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/12a4bddf1ea3c5d37f2233a4821909e9.png)
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2019-01-22更新
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3814次组卷
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4卷引用:吉林省长春市十一高中2020-2021学年高一下学期第三学程考试数学试题