1 . 如图,正方体
的棱长为1,E,F是线段
上的两个动点.
![](https://img.xkw.com/dksih/QBM/editorImg/2023/2/17/760ce406-4354-4748-bae8-c38cf1786997.png?resizew=163)
(1)若
平面
,求
的长度;
(2)若
,求直线
与平面
所成角的正弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6e09725691ee7851f54c0dee86b2bf55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8cfbc0b5a8fbde804bd8425a4b76d207.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/2/17/760ce406-4354-4748-bae8-c38cf1786997.png?resizew=163)
(1)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1c8ccd4181f956f6e0140bf0ab8f0716.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4c66d99a6a8415ddad22bbed33b64cfb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/49b50357a6545cae8348e3059312f520.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c4f0e4c327b18dcd54245e68e7477998.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/85c4bdfb0db1e31e8459df1d15f9ab55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4c66d99a6a8415ddad22bbed33b64cfb.png)
您最近一年使用:0次
2023-02-15更新
|
836次组卷
|
3卷引用:安徽省蚌埠市2023届高三下学期第二次教学质量检查数学试题
解题方法
2 . 《九章算术》记录形似“楔体”的所谓“羡除”,就是三个侧面都是梯形或平行四边形(其中最多只有一个平行四边形)、两个不平行对面是三角形的五面体.如图,羡除
中,
是正方形,且
,
均为正三角形,棱
平行于平面
,
.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/19/a5285efe-dced-40f2-a3cf-e76ba09aafef.png?resizew=233)
(1)求证:
;
(2)求二面角
的大小.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9165d9bfbb0f0d19eb482c2a4c1b29b7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6cb3e973f4e9361e1d23a0ab56006d12.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f6a0c85deb80d8e63bc60127e803f7ea.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/49b50357a6545cae8348e3059312f520.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9366db1b71034abbe1a5693689cf1c22.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/19/a5285efe-dced-40f2-a3cf-e76ba09aafef.png?resizew=233)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/51ae949669447e566b8f4d5938163a9a.png)
(2)求二面角
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/89c9c2c831a0552a7c934365bc49ad3f.png)
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