如图,在多面体ABCDEF中,四边形ACDE是正方形,DF//BC,AB⊥AC,AE⊥平面ABC,AB=AC=2,EF=DF=
.
![](https://img.xkw.com/dksih/QBM/2022/2/28/2926244105977856/2929928890179584/STEM/a786b5c568ec4c3897bcaba37cad87c8.png?resizew=186)
(1)求证:平面BCDF⊥平面BEF;
(2)求二面角A-BF-E的余弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cf298f00799cbf34b4db26f5f63af92f.png)
![](https://img.xkw.com/dksih/QBM/2022/2/28/2926244105977856/2929928890179584/STEM/a786b5c568ec4c3897bcaba37cad87c8.png?resizew=186)
(1)求证:平面BCDF⊥平面BEF;
(2)求二面角A-BF-E的余弦值.
更新时间:2022-03-05 22:58:29
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真题
【推荐1】如图,三角形△PDC所在的平面与长方形ABCD所在的平面垂直,PD=PC=4,AB=6,BC=3,点E是CD的中点,点F、G分别在线段AB、BC上,且AF=2FB,CG=2GB.
(1)证明:PE⊥FG;
(2)求二面角P﹣AD﹣C的正切值;
(3)求直线PA与直线FG所成角的余弦值.
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【推荐2】如图,在四棱锥
中,底面
是矩形,
平面
.
![](https://img.xkw.com/dksih/QBM/2020/8/8/2523555861856256/2524710068592640/STEM/a8a50b4492a347fb803125f23b4054f3.png?resizew=309)
(1)求证:
;
(2)若E是
的中点,F在
上,
平面
,求
的值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0585b6c0f156eecf9662b9846d4eb693.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5a1b49f64e0065edad868b25e9fcada3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://img.xkw.com/dksih/QBM/2020/8/8/2523555861856256/2524710068592640/STEM/a8a50b4492a347fb803125f23b4054f3.png?resizew=309)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ecf6c62979a7aa534a191d8387a741e8.png)
(2)若E是
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/48f3c9abbd78e9a6840ee5f30381daac.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f8c2b786c64e6a9ed2ec5670cde74f86.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/134ef0b1a2669a09f05bd4dc2496f706.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d9e0225c6d7f9c9125bcd7154285096d.png)
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【推荐3】如图,EA和DC都垂直于平面ABC,
,F,G分别是EB和AB的中点.求证:
平面ABC;
(2)
平面ABC.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8746ed1a83bff7ec2118a7a57c4fd539.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d88d863bbe0a300e8c2f464574c4f5e6.png)
(2)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15578524d13773ba35b7a879f5344eb6.png)
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【推荐1】在四棱锥
中,平面
平面
,
,
,
,
,
为棱
的中点,且
.
的高;
(2)求二面角
的正弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0585b6c0f156eecf9662b9846d4eb693.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/342d452a7b850cd3a15b23619ad39bd7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5f79863ffcfa63117ca6741b20a48e69.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/080db3af81b29ed10144a1c2e2a4fb8a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ec2d5ab801f2a84b78139b0ea2c5032b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a43c2d5aae759fc4db16115c8188ceec.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8f5ffe436f8eb53a211abf95baed8ca9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0585b6c0f156eecf9662b9846d4eb693.png)
(2)求二面角
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/db04e82f03e6216886d416b35abe85a3.png)
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【推荐2】如图,在正三棱柱
中,
,D,E,F分别为线段
,
,
的中点.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/4/821c54bd-f719-4b73-ad14-f7d56b09a101.png?resizew=145)
(1)证明:
平面
;
(2)证明:
平面
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/42d3a82b8e587ee890467835bc4e854c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/87d586ace3f9b8f58bac6f12d2b5dac3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4a696a182fff038a86b2bbe8ca099442.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/588eb9393564a33552c4b2e8de837ca5.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/4/821c54bd-f719-4b73-ad14-f7d56b09a101.png?resizew=145)
(1)证明:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/57f9d682e5d3cc8573574d8d11636758.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7bef5239ddbb0972700ce01daf9ee7cf.png)
(2)证明:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/af6ab0386dde0643de8caf33f946072f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/34be4e71cabf458f17a6cd7f24bc70af.png)
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【推荐3】如图,在三棱锥D-ABC中
为锐角三角形,平面ACD⊥平面
.
![](https://img.xkw.com/dksih/QBM/2020/6/17/2486854022299648/2487443876241408/STEM/6d47dd07fa484af385daa6b80ba504cc.png?resizew=184)
(1)求证:CD⊥平面ABC
(2)若直线BD与平面ACD所成角的正弦值为
,求二面角D-AB-C的余弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/49a5ed64eaa8f9572d819ed913d630ad.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ff7b345d2853ae437bc247cbf290757b.png)
![](https://img.xkw.com/dksih/QBM/2020/6/17/2486854022299648/2487443876241408/STEM/6d47dd07fa484af385daa6b80ba504cc.png?resizew=184)
(1)求证:CD⊥平面ABC
(2)若直线BD与平面ACD所成角的正弦值为
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/059d02ae074c7c2f7dfde8058dfa55ab.png)
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【推荐1】如图所示,四棱锥
中,平面
平面
,
为
的中点,
为
的中点,且AE∥DC,
,
.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/3/e5098406-0721-40ce-aa5a-a791676cbe82.png?resizew=165)
(Ⅰ)证明:平面
平面
;
(Ⅱ)若
,求三棱锥
的体积.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bc655b4d76a5b4d74271082ced237657.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6d732a13de1a080292bcd37a330f7b5d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7bef5239ddbb0972700ce01daf9ee7cf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d40b319212a7e7528b053e1c7097e966.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d7630e78a6a312c940718cc5908c2030.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e8520fa1d5d15aaad654e97ecf6e9c5c.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/3/e5098406-0721-40ce-aa5a-a791676cbe82.png?resizew=165)
(Ⅰ)证明:平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3547a914468b082d8d8741b974a03190.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ca67a5b8f69507c8b80379e86f90a8ce.png)
(Ⅱ)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/16ed75e65e7374c38ffb1f75259a8beb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d435a91c0447826d31158be0ce5a9e6d.png)
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【推荐2】如图,四棱锥
的底面是正方形,
底面
,
,
,点
,
分别为棱
,
的中点.
![](https://img.xkw.com/dksih/QBM/2011/9/14/1570311236280320/1570311241687040/STEM/f227d98f4ec74730a07f7f6061242016.png?resizew=297)
(1)在现有图形中,找出与
平行的平面,并给出证明;
(2)判断平面
与平面
是否垂直?若垂直,给出证明;若不垂直,说明理由.
![](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/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0b80ee363635d73f601654339028daec.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0e32cc188edc26012eb4e332c8b7b05d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e0629ce42392a7fe9be21d25c39c3e64.png)
![](https://img.xkw.com/dksih/QBM/2011/9/14/1570311236280320/1570311241687040/STEM/f227d98f4ec74730a07f7f6061242016.png?resizew=297)
(1)在现有图形中,找出与
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6aa2b5e09f8ec785c59900a529390a02.png)
(2)判断平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9068f29d671d76d1e95ba3a4eaff5b96.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/80f747eb5b2d21c9de962cbfd4ec4bb7.png)
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【推荐1】如图,在四棱锥
中,
底面ABCD,底面
为直角梯形,
,
,
,
.
(1)证明:
平面
;
(2)求平面
与平面
夹角的余弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/faeb97acf19bd3b2c6c77c2814df4d2f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/10c83f8945042b9c8fb2fbdac9308d62.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f571396be1aa4a8914a66f7d7abd6381.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/af260e0d98c95d1e092dc4c6d348e3ea.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ea91aeb7c52a6b4fb5ea9eaf8b6f79ab.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9ffbcd82b98a9ae69aa4ee28bb49a907.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/8/4/c100b592-95ac-4288-b816-8ae2a24a5676.png?resizew=101)
(1)证明:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e2ffc6952e988d04f22f0fb2f7f0ab7b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bc9c9cfa597b444b5c9dbae7a825a695.png)
(2)求平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bc9c9cfa597b444b5c9dbae7a825a695.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9ef796b46e68fe77b117ff0483d2370c.png)
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解题方法
【推荐2】如图,在直三棱柱
中,
,
,
、
分别为
、
的中点,设平面
交棱
于点
.
;
(2)求二面角
的平面角的正切值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/42d3a82b8e587ee890467835bc4e854c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/080db3af81b29ed10144a1c2e2a4fb8a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1a1ef1ea57ed911896ff5568c9998ac2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e0a851907ada2ac2c3c4880a6736d28a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/657dffbd3623b705f871878fbd9df57e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/274cf35acb4a1748d15c39d15a9bea7b.png)
(2)求二面角
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/12e69f1bfd13ddd15449f75343c221c9.png)
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