梯形ABCD中,
,
,
,
,将
沿AC折起,使平面
平面
.
![](https://img.xkw.com/dksih/QBM/editorImg/2023/2/2/d2d3771f-6063-4ecb-89a1-bda4740429ec.png?resizew=325)
(1)证明:
平面
;
(2)AC中点为M,求二面角
的余弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5f79863ffcfa63117ca6741b20a48e69.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4795ee1f96b430529934e2231b38885d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/633bf2de732ae51fc06ef3d559915da0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fcd0ced286a0fbc7e4862f8147264277.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/644f63756fe9251e65cc14e1ce9723d4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/de8ff58f671a287701011a1b31e67e28.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7bef5239ddbb0972700ce01daf9ee7cf.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/2/2/d2d3771f-6063-4ecb-89a1-bda4740429ec.png?resizew=325)
(1)证明:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ca5dd496ee0c1170ef6dcc48266ee444.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ca67a5b8f69507c8b80379e86f90a8ce.png)
(2)AC中点为M,求二面角
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/64785e4401e1d79632e360fd3626ed62.png)
更新时间:2022-04-17 22:45:07
|
相似题推荐
解答题-问答题
|
适中
(0.65)
名校
解题方法
【推荐1】如图①,△ABC中,AB=BC=2,∠ABC=90°,E,F分别为边AB,AC的中点,以EF为折痕把△AEF折起,使点A到达点P的位置(如图②),且PB=BE.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/25/0464062b-e932-464b-aa91-5e96687ddf7d.png?resizew=254)
(1)证明:EF⊥平面PBE;
(2)设N为线段PF上的动点(包含端点),求直线BN与平面PCF所成角的正弦值的最大值.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/25/0464062b-e932-464b-aa91-5e96687ddf7d.png?resizew=254)
(1)证明:EF⊥平面PBE;
(2)设N为线段PF上的动点(包含端点),求直线BN与平面PCF所成角的正弦值的最大值.
您最近一年使用:0次
解答题-证明题
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【推荐2】如图
,
是圆柱的上、下底面圆的直径,
是边长为2的正方形,
是底面圆周上不同于
两点的一点,
.
![](https://img.xkw.com/dksih/QBM/2017/9/19/1777177656385536/1777396726784000/STEM/784ff24931954655832ef26ab2b7b587.png?resizew=132)
(1)求证:
平面
;
(2)求二面角
的余弦值.
![](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/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/01c74a907dda6bb7d9d56d009d9df253.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c1364213f546b37f8764ddcb59e36ae4.png)
![](https://img.xkw.com/dksih/QBM/2017/9/19/1777177656385536/1777396726784000/STEM/784ff24931954655832ef26ab2b7b587.png?resizew=132)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/662698361c6b3ddaf0c28a3c87be53e0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f332555e65843f32f4c623098c6adc72.png)
(2)求二面角
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/24db75f4d450674182ccfe3236aabdd3.png)
您最近一年使用:0次
解答题-证明题
|
适中
(0.65)
【推荐3】已知四棱锥
中,
,
,
,
,M为
的中点.
![](https://img.xkw.com/dksih/QBM/editorImg/2024/1/29/ed08871d-580c-4457-95a9-58d2836ef262.png?resizew=158)
(1)求证:
平面
;
(2)若
,
,求二面角
的余弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0585b6c0f156eecf9662b9846d4eb693.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/62974d34de3a12418d6b700420afd1b2.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/307d38cc7012c328f1f22aa793fe76d7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e0629ce42392a7fe9be21d25c39c3e64.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2024/1/29/ed08871d-580c-4457-95a9-58d2836ef262.png?resizew=158)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6e0684e0b09b04661c602437982c0397.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1e582d73b96ba649378379c3074d506d.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c3b10835116b9b777a666b438c907b49.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cc1016bb201c2261d0f9774e85d2eefa.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/698335f4880c7a298f4898c83b6562bf.png)
您最近一年使用:0次
解答题-证明题
|
适中
(0.65)
名校
解题方法
【推荐1】如图,
为圆
的直径,
为圆周上异于
、
的一点,
垂直于圆
所在的平面,
于点
,
于点
.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/26/7b215bb1-6040-4c1a-9124-1a6818b0d9d2.png?resizew=141)
(1)求证:
;
(2)若
,
,求三棱锥
的体积.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1dde8112e8eb968fd042418dd632759e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1dde8112e8eb968fd042418dd632759e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d320f180419175d75eebc618cc458b39.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5b9d0c688e55286443c9974797fc647f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/26/7b215bb1-6040-4c1a-9124-1a6818b0d9d2.png?resizew=141)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8f2a245381e615882ee5feb7793a1df6.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f121eabff3c62c1a196d9ca5f6f83f0b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f1212f222bed8b39156d13de8a35f40f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/05925f665156215b1e031ea6c190616a.png)
您最近一年使用:0次
解答题-证明题
|
适中
(0.65)
名校
解题方法
【推荐2】如图,在四棱锥
中,底面
为菱形,
,
平面
,
,
为棱
的中点,点
在棱
上.
![](https://img.xkw.com/dksih/QBM/editorImg/2024/2/16/b60d8a12-434c-43b1-b2f6-48d3ae2941f5.png?resizew=156)
(1)证明:平面
平面
;
(2)若Q为
的中点,求直线
与平面
所成角的正弦值.
![](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/7ac94e7b9fbc2ad39be4f935f8cb5216.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/e3f6967901d6c855864df01e7bf7a15c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/acc290b44635265137fdf13146b6a6d9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d2be49c37e30a3ced0364c3e74d8c687.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2024/2/16/b60d8a12-434c-43b1-b2f6-48d3ae2941f5.png?resizew=156)
(1)证明:平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e57282b4f789e26c4f6223e4f8652ce0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3e6c2dad46a9052a4185a4f7b4ae8a2e.png)
(2)若Q为
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d2be49c37e30a3ced0364c3e74d8c687.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fc5adb5eb60ae4435a12d93854066298.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3c550269f3199038726f55cbd281c13a.png)
您最近一年使用:0次
解答题-证明题
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适中
(0.65)
【推荐3】如图
,在
中,
分别为
的中点,
为
的中点,
,
.将
沿
折起到
的位置,使得平面
平面
,如图
.
![](https://img.xkw.com/dksih/QBM/editorImg/2023/12/9/62276dd9-eaa0-4b09-bcba-ff3e6520bc0b.png?resizew=325)
(1)求证:
.
(2)线段
上是否存在点
,使得直线
和
所成角的余弦值为
?若存在,求出
的值;若不存在,说明理由.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bdaa19de263700a15fcf213d64a8cd57.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/91e1e4115d78e625e9e0f47cdade3286.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7dec2ca6438c82b43f746057d8129885.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1dde8112e8eb968fd042418dd632759e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e6e490f703eb6c9bb1278c78ebc2d661.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0117046e7a37bebe0c7b987a00d2bcb7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e65a3e478bb87d094e3a0af30dd10ae8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a25c28359f8d8da9eaf4672a6cf8ae4f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e6e490f703eb6c9bb1278c78ebc2d661.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3aa2a83fed9bf4cb09d84a980452e346.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d7b3e7c7845a0ec3cbac709fda131764.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/65c42bce098904b241986bb91c65ab33.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/61128ab996360a038e6e64d82fcba004.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/12/9/62276dd9-eaa0-4b09-bcba-ff3e6520bc0b.png?resizew=325)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4e51c4114e94bceb198403c1858b9682.png)
(2)线段
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3ee8456443402a25b1e25d35ff7e1c98.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d004d2d115b477ade6af7ddb93db0df8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a261474cc7607d31a6324cb4df9c8896.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c741af321a8ddaf387fa661f3920ad84.png)
您最近一年使用:0次
解答题-问答题
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适中
(0.65)
【推荐1】如图,四棱柱
的底面ABCD为矩形,
,M为BC中点,平面
,
且
.
![](https://img.xkw.com/dksih/QBM/2021/7/8/2759751327858688/2777755634409472/STEM/d8332bb3-75f6-4e8c-aeb4-2395e64a199e.png?resizew=303)
(1)证明:
.
(2)若此四棱柱的体积为2求二面角
的正弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6e09725691ee7851f54c0dee86b2bf55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1b929269c53a44907dba8ee298a0a522.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/849dcb00a09c2e4b5886671140f6d82f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/aff7ce58deed5cf5c76fd122e9afecfb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3c3232a80d0d71fe3f3f0af470b1aa1a.png)
![](https://img.xkw.com/dksih/QBM/2021/7/8/2759751327858688/2777755634409472/STEM/d8332bb3-75f6-4e8c-aeb4-2395e64a199e.png?resizew=303)
(1)证明:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fd0fda605131780ab8e11cb92ed5295d.png)
(2)若此四棱柱的体积为2求二面角
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ff420795b334c9934c366b99507d0026.png)
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【推荐2】把边长为2的正方形
沿对角线
折起,如图,点
翻折到点
,
![](https://img.xkw.com/dksih/QBM/editorImg/2023/12/2/6bd0d616-3d1c-4969-80fe-7af7795786ce.png?resizew=180)
(1)当折起的三角形
所在的平面与底面
所成角(即二面角
)为
时,求三棱锥
的体积;
(2)当三角形
翻折到什么位置(即二面角
多大时),三棱锥
的体积最大(不需要证明).并求此时三棱锥
的表面积.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/97c01fdc7bc471af0b264a04aef0823e.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/12/2/6bd0d616-3d1c-4969-80fe-7af7795786ce.png?resizew=180)
(1)当折起的三角形
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/13cfdc6224181d44e63aab43ddaf07ef.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b4eb7e9ad5486cf1c5e506b20c5469e8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/de25bd0a6911c52d0d319c2318a67ef7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac1a63ab608517bb10aa036783dfb51f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1ecc884f5b4dc9622e90e1303bc481f5.png)
(2)当三角形
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/13cfdc6224181d44e63aab43ddaf07ef.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/de25bd0a6911c52d0d319c2318a67ef7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1ecc884f5b4dc9622e90e1303bc481f5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1ecc884f5b4dc9622e90e1303bc481f5.png)
您最近一年使用:0次
解答题-问答题
|
适中
(0.65)
名校
【推荐1】已知在四棱锥
中,底面
为菱形,
平面
分别为
的中点,点
在棱
上移动.
![](https://img.xkw.com/dksih/QBM/2021/11/21/2856290267447296/2857328677593088/STEM/bb8bbc2e-c062-48ef-a59f-9ada7c90bde8.png?resizew=264)
(1)证明:无论
在棱
上如何移动都有平面
平面
;
(2)若
,在线段
上是否存在一点
,使得二面角
的正弦值为
.若存在,试确定
的位置;若不存在,说明理由.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/df5c044e1f89e113f1f4f63cf60c7518.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/84db0e7e60f8b5b9eb6016e1ff1d40b1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/266a45d9900154d94d896bca6cb7873c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/19935e386ac54c8257a4b9ea0bd9d7a6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/48f3c9abbd78e9a6840ee5f30381daac.png)
![](https://img.xkw.com/dksih/QBM/2021/11/21/2856290267447296/2857328677593088/STEM/bb8bbc2e-c062-48ef-a59f-9ada7c90bde8.png?resizew=264)
(1)证明:无论
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/48f3c9abbd78e9a6840ee5f30381daac.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6501f1c913a4ef64957a2f01ab5baa15.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/852aabd89edffc1b94344ff3f1f31ccd.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ced3d3dd6af84fb052fc7281d707853e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/48f3c9abbd78e9a6840ee5f30381daac.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ce747dfba7cd1b8054a3fc741629f257.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d83fb9ac8a18e78a4c56da79514b5ccb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
您最近一年使用:0次
解答题-问答题
|
适中
(0.65)
解题方法
【推荐2】如图1是一个正方形和一副直角三角板(常用的文具哟),其中
,
,将AD与
、BC与
分别重合,并将两个三角板翻起,使点
与点
重合于点P,得一几何体如图2.
![](https://img.xkw.com/dksih/QBM/2022/1/6/2851674979016704/2893688112996352/STEM/3c0d3ca3-78b2-4881-a21b-7bb42eefa08c.png?resizew=403)
(1)证明:直线AD⊥直线PC;
(2)求平面PAB与平面PCD的夹角的正弦值;
(3)在正方形面ABCD范围内有以圆心为D、半径为2的一段圆弧,则在该段圆弧上,是否存在点Q使得异面直线PC与DQ所成的角是
,试说明你的理由.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8c7c611e11c53684c67f0014fc8aefb7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d44a724b932126a1fc576217342626a5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/394c5d2f55221975503be8aa18022480.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/56f7ba05c54b3de1f4378f7c8eb58328.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2708fa6298e52f617383efc175b71ddc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9b9cb8e6ff801523b0304576cd69fd2d.png)
![](https://img.xkw.com/dksih/QBM/2022/1/6/2851674979016704/2893688112996352/STEM/3c0d3ca3-78b2-4881-a21b-7bb42eefa08c.png?resizew=403)
(1)证明:直线AD⊥直线PC;
(2)求平面PAB与平面PCD的夹角的正弦值;
(3)在正方形面ABCD范围内有以圆心为D、半径为2的一段圆弧,则在该段圆弧上,是否存在点Q使得异面直线PC与DQ所成的角是
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2d88591679796c52024d11c4de641bdb.png)
您最近一年使用:0次
解答题-证明题
|
适中
(0.65)
名校
【推荐3】如图,在直三棱柱
中,底面是等腰直角三角形,
,侧棱
,点
分别为棱
的中点,
的重心为
,直线
垂直于平面
.
![](https://img.xkw.com/dksih/QBM/2017/11/16/1818333004242944/1818958867210240/STEM/67b97cc20c264ed999eb3890d9776092.png?resizew=143)
(1)求证:直线
平面
;
(2)求二面角
的余弦.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/42d3a82b8e587ee890467835bc4e854c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/571ef38fc225d102bcd4f35bab70078c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/92535536bd3c2761724fd058427f95a8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/927456b0989846a2f1573844bbaa2105.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/40f00568da99b65b6f8353aeb5805003.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/db5e1441a49e782ff0ef46e776cde06a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/895dc3dc3a6606ff487a4c4863e18509.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/31e55e398e8520d8a36fb5a625a085b8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7abd284f76d9f5769bc189508ce2572b.png)
![](https://img.xkw.com/dksih/QBM/2017/11/16/1818333004242944/1818958867210240/STEM/67b97cc20c264ed999eb3890d9776092.png?resizew=143)
(1)求证:直线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/94270844f197d524bf1da4f1385befd2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7935fe3125f247b7bea4f065ce9ad985.png)
(2)求二面角
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7e18b48c0263fbc4cbf072b7662589e2.png)
您最近一年使用:0次