名校
1 . 如图,正三棱柱
中,侧棱
,
,
分别为棱
的中点,
分别为线段
和BE的中点.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/8/18/a523556c-07f0-449f-a36b-15c4e40d0eab.png?resizew=257)
(1)求证:直线
平面
;
(2)求二面角
的余弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/42d3a82b8e587ee890467835bc4e854c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6db57eca2a7cbd91bc57372592580a76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fcd0ced286a0fbc7e4862f8147264277.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/91e1e4115d78e625e9e0f47cdade3286.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9debd13454918684cf8e07ce210516fc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7789a500686c7a73770404ead6af0590.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/24bb49fdc6b6bbb2449fdf8a0de769d3.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/8/18/a523556c-07f0-449f-a36b-15c4e40d0eab.png?resizew=257)
(1)求证:直线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/edcf19a7f0dd0cdf59516ae585025110.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7bef5239ddbb0972700ce01daf9ee7cf.png)
(2)求二面角
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9df77527db5d65c2f4a0e7d308a52530.png)
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2017-06-02更新
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2卷引用:江西省南昌市南昌县莲塘一中2018届直升班周末练试卷数学试题