图1是由矩形
、
和菱形
组成的一个平面图形,其中
,
,
.将其沿
,
折起使得
与
重合,连接
,如图2.
(1)证明:图2中的
,
,
,
四点共面,且平面
平面
;
(2)求图2中
与平面
所成角的正弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d498a0467ff3c577a7ed175d7bffd885.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dd967903ed5a6f640a5b801ec8be0070.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f0da522aef3c452767df89b8d0eb62de.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ced06b71073e1bb777f326f06016ce17.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/de93a4fa2069aed282b7a97a4b41afbc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a02308f73ae93b7a077cea6f9bd1660.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/85c4bdfb0db1e31e8459df1d15f9ab55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/274cf35acb4a1748d15c39d15a9bea7b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1e72b2e1ff83e95df048745322982451.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/8/5/8674f3d0-6f2f-409f-8e72-e95e8c30916f.png?resizew=347)
(1)证明:图2中的
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/895dc3dc3a6606ff487a4c4863e18509.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a3d7090639341730951c1bc3c9b6164e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/693cd6179b2a92f03153ce12a0e86b95.png)
(2)求图2中
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/06e322e0c87479bba874db9ae9ba36b5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ab3df0d9a6c83b35a863544a01f22ef7.png)
更新时间:2023-08-02 16:43:57
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【推荐1】已知空间几何体ABCDE中,
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(2)若
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【推荐2】如图,四棱锥
的底面是矩形,PA⊥底面ABCD,
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.
![](https://img.xkw.com/dksih/QBM/editorImg/2023/2/22/36dc1423-0da9-4eac-9718-9d3739db7b90.png?resizew=160)
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0585b6c0f156eecf9662b9846d4eb693.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c406e7d1e7977dd5b30ef81cfdc8e8d2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/267ace52b64e1e7dfc5211e033255b7d.png)
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(1)证明:B,M,N,K四点共面;
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【推荐1】如图,在五面体
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的正方形,
,
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b8860d9787671b53b1ab68b3d526f5ca.png)
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/686171942bd7698035016c732db43b63.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3fc5653b8818c02e71dc54027b175256.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/79c1acdd27cebb11e0266464b03b3afb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://img.xkw.com/dksih/QBM/2021/3/30/2689172677623808/2689737262284800/STEM/c9e93d2e-26d3-4cf2-ae0e-89f306108240.png?resizew=302)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b8d2d217e9bcd059908f117dfc4d4259.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/22d1a8ed65b138016acff8c465165337.png)
(2)求二面角
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e4b820c84570da9c38d0a81c22788b76.png)
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【推荐2】如图所示,在棱长为2的正方体ABCD﹣A1B1C1D1中,E、F分别为DD1、DB的中点.
![](https://img.xkw.com/dksih/QBM/2020/1/4/2369701273042944/2370058151641088/STEM/c3a893a5077a4ed9809bd6e7d3bfe05c.png?resizew=193)
(1)求证:EF∥平面ABC1D1;
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(1)求证:EF∥平面ABC1D1;
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【推荐1】在四棱锥
中,底面
是
,边长为2的菱形.又
底面
,且
,点
,
分别是棱
,
的中点.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/23/1252759d-e13a-4104-b7ac-d1ecd6abc6e6.png?resizew=204)
(1)证明:
平面
;
(2)证明:平面
平面
;
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![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/23/1252759d-e13a-4104-b7ac-d1ecd6abc6e6.png?resizew=204)
(1)证明:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6824aefcb90c571b1699a22592bdf037.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2b81fb655624ff75a5eab94de9b8c8e9.png)
(2)证明:平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6507d6b6ca4c46d3f05ba63f2718c3d9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/852aabd89edffc1b94344ff3f1f31ccd.png)
(3)求点A到平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2b81fb655624ff75a5eab94de9b8c8e9.png)
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【推荐2】如图,已知ABCD是边长为2的正方形,
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【推荐1】如图1,在边长为4的等边中,
,
分别是
,
的中点.将
沿
折至
(如图2),使得
.
(1)证明:平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4ac48b9ac8efbf41d6ab5242d247bd89.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2fa7bbd7831e9ff4f8cffc8889d34f05.png)
(2)若点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e0629ce42392a7fe9be21d25c39c3e64.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8e5c62f22d7afc5627fcb86599faa8e1.png)
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【推荐2】如图,在四棱锥
中,
,
,Q是AD的中点,
,
,
,![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ff0a0c299356c26338d4153748e8a61d.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/10/d6081d06-7980-4008-90c9-55918f94fa1d.png?resizew=154)
(1)求证:平面
平面
;
(2)求直线
与平面
所成角的正切值
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/39824188969f46dba05c56ea293ebbc6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d04140df8b6986b5ec855a6059c4cb2f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9e8798a8c90003720f58a819ea05437d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e8254b52b379a420c17d38334940b073.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5729dd997ea7e8cb4cef8b7165b36e00.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/18120a244d3a1f9c1688bf53eb2ad775.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ff0a0c299356c26338d4153748e8a61d.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/10/d6081d06-7980-4008-90c9-55918f94fa1d.png?resizew=154)
(1)求证:平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/93edc7bb513f40a89173121c8570cd65.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
(2)求直线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/48f3c9abbd78e9a6840ee5f30381daac.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/852aabd89edffc1b94344ff3f1f31ccd.png)
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