如图,四面体
中,
分别是
的中点,![](https://img.xkw.com/dksih/QBM/2018/1/25/1868040102723584/1868950830022656/STEM/940f3b1349f242c6b0920c61e21e6fc3.png?resizew=229)
![](https://img.xkw.com/dksih/QBM/2018/1/25/1868040102723584/1868950830022656/STEM/34c436ee940b42629800cdc93f932137.png?resizew=144)
(1)求证:
平面
;
(2)求直线
与平面
所成角的正弦值.
![](https://img.xkw.com/dksih/QBM/2018/1/25/1868040102723584/1868950830022656/STEM/d401d3bc90a54f369af75f4cd53d2112.png?resizew=48)
![](https://img.xkw.com/dksih/QBM/2018/1/25/1868040102723584/1868950830022656/STEM/07eb632669dc4cde8faea1f75b4feb0e.png?resizew=43)
![](https://img.xkw.com/dksih/QBM/2018/1/25/1868040102723584/1868950830022656/STEM/5689b0eef29e4ca7862381e4965e2702.png?resizew=64)
![](https://img.xkw.com/dksih/QBM/2018/1/25/1868040102723584/1868950830022656/STEM/940f3b1349f242c6b0920c61e21e6fc3.png?resizew=229)
![](https://img.xkw.com/dksih/QBM/2018/1/25/1868040102723584/1868950830022656/STEM/34c436ee940b42629800cdc93f932137.png?resizew=144)
(1)求证:
![](https://img.xkw.com/dksih/QBM/2018/1/25/1868040102723584/1868950830022656/STEM/97f07fe9481845a5b57023cb8d29c939.png?resizew=39)
![](https://img.xkw.com/dksih/QBM/2018/1/25/1868040102723584/1868950830022656/STEM/1dccb4a118b743d29748a02c0db59637.png?resizew=39)
(2)求直线
![](https://img.xkw.com/dksih/QBM/2018/1/25/1868040102723584/1868950830022656/STEM/222cecc00c924b1e8bd03c0f4bf04e1b.png?resizew=28)
![](https://img.xkw.com/dksih/QBM/2018/1/25/1868040102723584/1868950830022656/STEM/019d101daf1a46ad844e2dc1ec267b08.png?resizew=39)
更新时间:2018-01-26 22:53:06
|
相似题推荐
解答题-问答题
|
适中
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解题方法
【推荐1】如图所示,在直三棱柱
中,
是边长为4的等边三角形,D,E分别为
,BC的中点.
![](https://img.xkw.com/dksih/QBM/2021/6/2/2734571141545984/2734870896795648/STEM/5b5536951fd041d89f4a93fb27d0ab67.png?resizew=368)
(1)证明:
平面
;
(2)若
,求点E到面
的距离.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/42d3a82b8e587ee890467835bc4e854c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2777840758e70e7dbbc18cef8f3d6d2b.png)
![](https://img.xkw.com/dksih/QBM/2021/6/2/2734571141545984/2734870896795648/STEM/5b5536951fd041d89f4a93fb27d0ab67.png?resizew=368)
(1)证明:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c6ae72f5e5891249caa10c43224da89c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6bf9628142422a4884bd59538da6d312.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/42da806a6bd2472459f6c4ad1dab7b29.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6bf9628142422a4884bd59538da6d312.png)
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【推荐2】如图,圆锥的顶点为
,底面圆心为
,线段
和线段
都是底面圆的直径,且直线
与直线
的夹角为
,已知
,
.
(1)求该圆锥的体积;
(2)求证:直线
平行于平面
,并求直线
到平面
的距离.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1dde8112e8eb968fd042418dd632759e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b1ad72d7565699d1ebb741eb0ce12bac.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9a1dbd8216f733bdb41f8da7f4c4a174.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/eec32de15bc2b5ac95cb1d3082fd6f2c.png)
(1)求该圆锥的体积;
(2)求证:直线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8f571a1aac46c6d0cf440c0ec2846bf9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8f571a1aac46c6d0cf440c0ec2846bf9.png)
![](https://img.xkw.com/dksih/QBM/2017/6/27/1718136259543040/1720852391985152/STEM/829509082161447b95ef2fa1ba8edea2.png?resizew=146)
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【推荐3】如图,在棱长为1的正方体ABCD﹣A1B1C1D1中,点E是BB1的中点,点F在棱AB上,且AF=2FB,设直线BD1、DE相交于点G.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/16/266d5a6e-d9b6-4f1e-b50a-e6a754639733.png?resizew=170)
(1)证明:GF∥平面A1A1D1D.
(2)求二面角D﹣CE﹣D1的余弦值.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/16/266d5a6e-d9b6-4f1e-b50a-e6a754639733.png?resizew=170)
(1)证明:GF∥平面A1A1D1D.
(2)求二面角D﹣CE﹣D1的余弦值.
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【推荐1】已知在三棱台
中,
,
,
平面
.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/24/204671dd-5b2c-48ff-bffd-a733ecac0222.png?resizew=191)
(1)证明
;
(2)若
为
的中点,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/248bc27537545a5d8cd74d73323b5472.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f656e1d1f68954e5f06de8958f6a9310.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d25e8fc3dda4f8b45491514b6e22a962.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/99b16cff607cdc2d69afc70dc778acbb.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/24/204671dd-5b2c-48ff-bffd-a733ecac0222.png?resizew=191)
(1)证明
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ffeea0a84cdd67bd8bed95bc0f8ae364.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0f1f229274a6e17977cc047814212589.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e26d9636ad77369535852c6e4493446a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a5bc0580c6c53d00438fcf63bcbc5179.png)
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【推荐2】如图;正四棱柱
中;
;点
为
的中点.
(1)求证:直线
平面
;
(2)求直线
与平面
所成线面角的正弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6e09725691ee7851f54c0dee86b2bf55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c6c5282bc1ea20767a6c092c22c761ca.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/22adbc0da438220f9cace11b629d799b.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/7/24/35b9ceee-2832-47a5-ab26-13a995fe2905.png?resizew=155)
(1)求证:直线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/923d409630f5331cf8e85fb6c584e31b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0628681907ac8d7fdb94d8bc1b15feb9.png)
(2)求直线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0d8772aa893a9c1d40f714cb25701701.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cf4c26f3f4d96117f087400a0f32ece8.png)
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【推荐1】正四棱柱
中,
,
为
中点,
为
中点.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/29/bdea8d9d-cb7d-45a7-9a1a-193f94beef2b.png?resizew=160)
(1)证明:
平面
;
(2)若
,求直线
与平面
所成的角.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6e09725691ee7851f54c0dee86b2bf55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d262480ffb55b7617f44b63f130c154a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e0a851907ada2ac2c3c4880a6736d28a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/03902478df1a55bc99703210bccab910.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/29/bdea8d9d-cb7d-45a7-9a1a-193f94beef2b.png?resizew=160)
(1)证明:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e9d32e76582bf550593fdef53e081225.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7850e88507969a07a9515347b97c7b6e.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/92535536bd3c2761724fd058427f95a8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7850e88507969a07a9515347b97c7b6e.png)
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解题方法
【推荐2】在如图所示的试验装置中,两个正方形框架ABCD,ABEF的边长都是1,且它们所在的平面互相垂直.活动弹子M,N分别在正方形对角线AB,BF上移动,且CM,BN的长度保持相等,记
.
(1)求异面直线AC,BF所成角的余弦值;
(2)a为何值时,MN的长最小?
(3)当MN的长最小时,求AB与平面AMN夹角的余弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4ec6a9edd2407d0bb7a628a8f2a27c9a.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/11/19/551f2680-acd4-4e5d-9ad2-3a6518707afb.png?resizew=124)
(1)求异面直线AC,BF所成角的余弦值;
(2)a为何值时,MN的长最小?
(3)当MN的长最小时,求AB与平面AMN夹角的余弦值.
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