如图,正方体
中,
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6e09725691ee7851f54c0dee86b2bf55.png)
(1)求证:平面
;
(2)求直线与平面
所成角的正弦值.
更新时间:2018-12-15 16:26:56
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解答题-证明题
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【推荐1】如图,在四棱锥
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【推荐2】如图,
平面
,
,
,
为
的中点.
(1)求证:
平面
;
(2)求二面角
的余弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ccd4fd4b7a4d6b8ca0c5827c055a9ce7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7bef5239ddbb0972700ce01daf9ee7cf.png)
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/be5d1bfdfd201164a16ee8cc4644a984.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d2be49c37e30a3ced0364c3e74d8c687.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/11/4/5c881d9b-0331-4582-bf3a-7486a22bec24.png?resizew=160)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7d0edb1508fc95765f3bb316bcb5252d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e7b7c83470489253394bd288d7c920df.png)
(2)求二面角
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a438393ddfc7da1804baf4932442bb35.png)
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【推荐1】如图1,在直角梯形ABCD中,
,
,
,
,E在AB上,且
为边长为2的等边三角形.将
沿DE折起,使得点A到点P的位置,平面
平面BCDE,如图2.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/7/24/4fdb590d-732c-43c5-80d9-2e3e758ec35b.png?resizew=304)
(1)若F为PC的中点,证明
平面PDE;
(2)证明:
;
(3)求直线BP与平面DCBE所成角的大小.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b0fff774b4b0087a6f304ce930d359be.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60d9142db4dd2ef151bf3d4a63afb61e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/efc6e4b936d7a800e839a30c3839574d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/833cfda415649b832cc136caed392753.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a25c28359f8d8da9eaf4672a6cf8ae4f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a25c28359f8d8da9eaf4672a6cf8ae4f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4ac48b9ac8efbf41d6ab5242d247bd89.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/7/24/4fdb590d-732c-43c5-80d9-2e3e758ec35b.png?resizew=304)
(1)若F为PC的中点,证明
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a4d888c0b616792a2c41ff180de99fbb.png)
(2)证明:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5c383691e8d740830a865b12d66f7633.png)
(3)求直线BP与平面DCBE所成角的大小.
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解题方法
【推荐2】已知正三棱柱
的底面边长为2,D是
的中点,![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8b2586e0bb827b0f1739e6ab36c0d62c.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/29/5d932a24-62fa-4208-af51-d9a1cebe80aa.png?resizew=261)
(1)求三棱柱
的体积
(2)求直线
与平面
所成角的正弦值
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/42d3a82b8e587ee890467835bc4e854c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e0a851907ada2ac2c3c4880a6736d28a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8b2586e0bb827b0f1739e6ab36c0d62c.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/29/5d932a24-62fa-4208-af51-d9a1cebe80aa.png?resizew=261)
(1)求三棱柱
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/42d3a82b8e587ee890467835bc4e854c.png)
(2)求直线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b470c4e195cf7a07b7a331ce4b436e03.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/62a52848aff08399a36f217356007a4b.png)
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