解题方法
1 . 在如图所示的六面体中,四边形ABCD是边长为2的正方形,四边形ABEF是梯形,
,平面
平面ABEF,BE=2AF=2,EF
.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/1/7bdd7d5b-cfe5-4383-a128-6a9558fd4a51.png?resizew=147)
(1)在图中作出平面ABCD与平面DEF的交线,并写出作图步骤,但不要求证明;
(2)求证:
平面DEF;
(3)求平面ABEF与平面ECD所成锐二面角的余弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dd3e927b7b2383ccded03838ae8b30b6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4cf9a6db3571fa57bfa2d5e4d44c51b3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a7ffe8515ff6183c1c7775dc6f94bdb8.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/1/7bdd7d5b-cfe5-4383-a128-6a9558fd4a51.png?resizew=147)
(1)在图中作出平面ABCD与平面DEF的交线,并写出作图步骤,但不要求证明;
(2)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8197bf06d017950c85c3ba6a291c095e.png)
(3)求平面ABEF与平面ECD所成锐二面角的余弦值.
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解题方法
2 .
,
为空间中两条互相垂直的直线,等腰直角三角形
的直角边
所在直线与
,
都垂直,斜边
以直线
为旋转轴旋转,有下列结论:①当直线
与
成
角时,
与
成
角;②当直线
与
成
角时,
与
成
角;③直线
与
所成角的最大值为
;④直线
与
所成角的最小值为
;其中正确的是___________ (填写所有正确结论的编号)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a6936d370d6a238a608ca56f87198de.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2c94bb12cee76221e13f9ef955b0aab1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7bef5239ddbb0972700ce01daf9ee7cf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a6936d370d6a238a608ca56f87198de.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2c94bb12cee76221e13f9ef955b0aab1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a6936d370d6a238a608ca56f87198de.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/be6a6301878fed2a01413020b27310a5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2c94bb12cee76221e13f9ef955b0aab1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/be6a6301878fed2a01413020b27310a5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a6936d370d6a238a608ca56f87198de.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/be6a6301878fed2a01413020b27310a5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2c94bb12cee76221e13f9ef955b0aab1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f6b86c22b670a8e9f3896f9e8883fbbb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a6936d370d6a238a608ca56f87198de.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/be6a6301878fed2a01413020b27310a5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a6936d370d6a238a608ca56f87198de.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f6b86c22b670a8e9f3896f9e8883fbbb.png)
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3 . 已知四棱锥
的底面ABCD是平行四边形,侧棱
平面ABCD,点M在棱DP上,且
,点N是在棱PC上的动点(不为端点).
![](https://img.xkw.com/dksih/QBM/editorImg/2022/9/30/3ca3f34b-c460-4557-a4c9-0502b91ee703.png?resizew=220)
(1)若N是棱PC中点,完成:
(i)画出
的重心G(在图中作出虚线),并指出点G与线段AN的关系:
(ii)求证:![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d2be49c37e30a3ced0364c3e74d8c687.png)
平面AMN;
(2)若四边形ABCD是正方形,且
,当点N在何处时,直线PA与平面AMN所成角的正弦值取最大值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0585b6c0f156eecf9662b9846d4eb693.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ccd4fd4b7a4d6b8ca0c5827c055a9ce7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fc85ce5e111acf7162b8e1b5a3f6b220.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/9/30/3ca3f34b-c460-4557-a4c9-0502b91ee703.png?resizew=220)
(1)若N是棱PC中点,完成:
(i)画出
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/acee03d4bb4667b6c345221b6c9b0fa4.png)
(ii)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d2be49c37e30a3ced0364c3e74d8c687.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/638537c0a30676c73fea76c80e0f8bd0.png)
(2)若四边形ABCD是正方形,且
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f2304c541406034dd83040e9a7887ed7.png)
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