如图,在四棱锥
中,四边形ABCD是菱形,
,
,三棱锥
是正三棱锥,E,F分别为
,
的中点.
![](https://img.xkw.com/dksih/QBM/editorImg/2023/5/4/bcf4acd6-d07b-4571-9cc1-eb73d927c625.png?resizew=214)
(1)求二面角
的余弦值;
(2)判断直线SA与平面BDF的位置关系.如果平行,求出直线SA与平面BDF的距离;如果不平行,说明理由.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/faeb97acf19bd3b2c6c77c2814df4d2f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ced06b71073e1bb777f326f06016ce17.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/76d4992bc4185d1a3ca52efb27425b5e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/69dd9f16a5c7a66e62e52fd66f4449ee.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8a6e2867f32d3f1c3cd36cd3a11a8580.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2c2bc5e50b8dfa02601c70822252854a.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/5/4/bcf4acd6-d07b-4571-9cc1-eb73d927c625.png?resizew=214)
(1)求二面角
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7267f2934c256fd74e58cb62d685bba0.png)
(2)判断直线SA与平面BDF的位置关系.如果平行,求出直线SA与平面BDF的距离;如果不平行,说明理由.
更新时间:2023-04-28 17:34:25
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【推荐1】如图1,在△ABC中,D,E分别为AB,AC的中点,O为DE的中点,
,BC=4.将△ADE沿DE折起到△
的位置,使得平面
平面BCED, F为A1C的中点,如图2.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/30/2903039b-bb8a-40e6-b78c-b99092b480f8.png?resizew=313)
(1)求证EF∥平面
;
(2)求点C到平面
的距离.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0117046e7a37bebe0c7b987a00d2bcb7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/657dffbd3623b705f871878fbd9df57e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d7b3e7c7845a0ec3cbac709fda131764.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/30/2903039b-bb8a-40e6-b78c-b99092b480f8.png?resizew=313)
(1)求证EF∥平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7935fe3125f247b7bea4f065ce9ad985.png)
(2)求点C到平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cb88c278e18d776f165bc571031071d8.png)
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【推荐2】如图,四边形ABCD是圆柱OE的轴截面,点F在底面圆O上,圆O的半径为1,
,点G是线段BF的中点.
平面DAF;
(2)若直线DF与圆柱底面所成角为45°,求点G到平面DEF的距离.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2f414cce1427646590a7f7144efe2e26.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f31d54d125c042169e282f14eddd45a1.png)
(2)若直线DF与圆柱底面所成角为45°,求点G到平面DEF的距离.
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【推荐1】已知四棱柱
,底面
是正方形,
平面
,
,
是侧棱
上的一点.
![](https://img.xkw.com/dksih/QBM/editorImg/2023/2/23/75d85d45-b9ba-4982-9be5-570dd088c0c9.png?resizew=143)
(1)求证:不论
在侧棱
上何位置,总有
;
(2)若
,求平面
与平面
所成二面角的余弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6e09725691ee7851f54c0dee86b2bf55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5845ccc0d735dc14c92a8926d9b1def6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.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/9d88bf46ad08f9677c37eed1d0369329.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/2/23/75d85d45-b9ba-4982-9be5-570dd088c0c9.png?resizew=143)
(1)求证:不论
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d88bf46ad08f9677c37eed1d0369329.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/55e1de129bfc451f4c7160cc50666ad8.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3f09f3ecd757cf5ec62b2bf3ac256b4f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b4704cbf3d2de2f06a6ee29b3c252109.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
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【推荐2】三棱柱
中,
平面
,且
,
为
中点.
(1)求四面体
的体积:
(2)求平面
与
所成锐二面角的余弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/42d3a82b8e587ee890467835bc4e854c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5845ccc0d735dc14c92a8926d9b1def6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7bef5239ddbb0972700ce01daf9ee7cf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/829018a6ca0aff95d89e3f7cd943274e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d3b891004d43a7656db1ffb7c107ad93.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d88bf46ad08f9677c37eed1d0369329.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2024/4/9/91d2b5bf-19dd-4fea-b8a4-87e4bffee1f3.png?resizew=144)
(1)求四面体
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cb650f48c879ea25127662b47d16feec.png)
(2)求平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7abd284f76d9f5769bc189508ce2572b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/13cfdc6224181d44e63aab43ddaf07ef.png)
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【推荐1】如图,四棱锥P-ABCD的底面为梯形,
底面ABCD,
,
,
,E为PA的中点.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/28/c4d7cea7-efc3-4bc2-a2d6-6951675003dd.png?resizew=207)
(1)证明:平面
平面BCE;
(2)若二面角P-BC-E的余弦值为
,求三棱锥P-BCE的体积.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5a1b49f64e0065edad868b25e9fcada3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c04230d9ddfa812c84339856d598f49c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5679a74e9f5506266ab627894ab03243.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/833cfda415649b832cc136caed392753.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/28/c4d7cea7-efc3-4bc2-a2d6-6951675003dd.png?resizew=207)
(1)证明:平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f04c222223dae9ef27d4c132534d9848.png)
(2)若二面角P-BC-E的余弦值为
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0b2215de6d4986954c95a5b711fd05aa.png)
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【推荐2】如图,在四棱锥
中,平面
平面
,
,
,
,
,
,
.
![](https://img.xkw.com/dksih/QBM/2020/11/17/2595117838630912/2597011214073856/STEM/c0fec333f2d74964bd4a6ffc9a57d88a.png?resizew=199)
(1)证明:
;
(2)求二面角
的余弦值;
(3)求点
到平面
的距离.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0585b6c0f156eecf9662b9846d4eb693.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/93edc7bb513f40a89173121c8570cd65.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d0453cfd7e92bf7746a88280b9e7b580.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/62974d34de3a12418d6b700420afd1b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1134c8e3440abb6cd385af2c169037fe.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ced06b71073e1bb777f326f06016ce17.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/09d27bd71d79cb19eb554175e4ef0867.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/958330f56d75b05fbf9144e6fd458be4.png)
![](https://img.xkw.com/dksih/QBM/2020/11/17/2595117838630912/2597011214073856/STEM/c0fec333f2d74964bd4a6ffc9a57d88a.png?resizew=199)
(1)证明:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7c583493109d50c9e4634c05e9042a9f.png)
(2)求二面角
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1636b4530c0b42d0e0b649e90e3b9e85.png)
(3)求点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/80f747eb5b2d21c9de962cbfd4ec4bb7.png)
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