1 . 如图,在四棱锥
中,
为等边三角形,平面
平面
,
,
,
,
,
为
的中点.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/10/28/8f66378a-d9c1-4c68-ba07-30e33819c0b8.png?resizew=221)
(1)求证:
;
(2)求二面角
的余弦值;
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e409a3a0db612b3fbe8f26bc40e83e63.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4c105d6ba18fbb0581fb982175e2eac9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6501f1c913a4ef64957a2f01ab5baa15.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a03952d664fba91020fc5f3bcf2f9746.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/476b0b8378f4b0f73f3dc5d84d89f616.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e65a3e478bb87d094e3a0af30dd10ae8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/50f85543243052612fb75694d6978bb8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9e9af0f7538dc8fc5683ef4959a11c53.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/701f3b0e2bedfe5195443459072d798e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/49b50357a6545cae8348e3059312f520.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/10/28/8f66378a-d9c1-4c68-ba07-30e33819c0b8.png?resizew=221)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7cd4d3ed0d4f1a2296de6a91445376f2.png)
(2)求二面角
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3541d43bfeba7f5a5cf0112b93932020.png)
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2016-12-04更新
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254次组卷
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2卷引用:北京市门头沟区大峪中学2021-2022学年高二上学期期中数学试题