解题方法
1 . 已知正方体
的棱长为2,
分别为
的中点.
![](https://img.xkw.com/dksih/QBM/2021/3/9/2674139275198464/2677682265489408/STEM/1e7eb36395414108a4e9749b4856e6e6.png?resizew=260)
(1)画出平面
截正方体各个面所得的多边形,并说明多边形的形状和作图依据;
(2)求二面角
的余弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6e09725691ee7851f54c0dee86b2bf55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0b199a99e53d67ff4abf233930961a29.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e21de25a662ba9e513dee5d6e34cb237.png)
![](https://img.xkw.com/dksih/QBM/2021/3/9/2674139275198464/2677682265489408/STEM/1e7eb36395414108a4e9749b4856e6e6.png?resizew=260)
(1)画出平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ffe8a84ca3a13f82aff1a022edc66065.png)
(2)求二面角
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fe5cf7b987c8da3b08450400484db716.png)
您最近一年使用:0次
2021-03-14更新
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4卷引用:宁夏银川市贺兰县景博中学2021届高三下学期二模数(理)试题
宁夏银川市贺兰县景博中学2021届高三下学期二模数(理)试题广西桂林、崇左市2021届高三二模数学(理)试题(已下线)专题36 仿真模拟卷04-2021年高考数学二轮复习热点题型精选精练(新高考地区专用)(已下线)精做04 立体几何-备战2021年高考数学(理)大题精做
名校
解题方法
2 . 如图,在直角梯形
中,
,
,
,
,现将平面图形沿
折成一个直二面角,得到四棱锥
,E,F分别为侧棱
、
的中点.
![](https://img.xkw.com/dksih/QBM/2021/5/2/2712383210962944/2716480608976896/STEM/952875df-244f-44ea-9c61-a94dd71b47ad.png?resizew=132)
(1)如图,在箭头右侧画出四棱锥
的直观图(不要求精确图形);
(2)证明:平面
平面
;
(3)若
是平面
的一个法向量,求
与平面
所成锐二面角的余弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4864c21e9664fa9111ede6425b09563a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3185a8075eea774ea1c6298fd1d0f5af.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c4340375ca8abdbd6998760c944f38d4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4cfc3c31464d82f3eac4777b046ca69a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a45024b1f1c50249cc194e8689ec01cc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0585b6c0f156eecf9662b9846d4eb693.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e0629ce42392a7fe9be21d25c39c3e64.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d2be49c37e30a3ced0364c3e74d8c687.png)
![](https://img.xkw.com/dksih/QBM/2021/5/2/2712383210962944/2716480608976896/STEM/952875df-244f-44ea-9c61-a94dd71b47ad.png?resizew=132)
(1)如图,在箭头右侧画出四棱锥
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0585b6c0f156eecf9662b9846d4eb693.png)
(2)证明:平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6501f1c913a4ef64957a2f01ab5baa15.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/80f747eb5b2d21c9de962cbfd4ec4bb7.png)
(3)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/49163e9dc6878910a10d2b4aa1ddad93.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e170f206fdbbd834aad7580c727e2cc6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e170f206fdbbd834aad7580c727e2cc6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b03428a8f91a5674cb8f54766c165f7e.png)
您最近一年使用:0次