如图,在四棱锥
中,底面
是正方形,
,
.
![](https://img.xkw.com/dksih/QBM/editorImg/2023/1/6/3c3a875b-b1de-45b0-88a3-9c6d5a7ef5a8.png?resizew=216)
(1)证明:
平面
;
(2)若
是
的中点,
是棱
上一点,且
平面
,求二面角
的余弦值.
![](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/0e7b6d04f024ca05cdfacc8ce9137c15.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/90ce2e773ee3f553baf5d56582c6ade1.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/1/6/3c3a875b-b1de-45b0-88a3-9c6d5a7ef5a8.png?resizew=216)
(1)证明:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5a5928c98b341b16d4b5a5b931d2929d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0628681907ac8d7fdb94d8bc1b15feb9.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.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/e0629ce42392a7fe9be21d25c39c3e64.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c372d059202ec388960b125d4a87dc84.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4734735213b599a9915e1ed91a5d8ce4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/281177cc5c7e6294a474dc64ee02aa29.png)
更新时间:2019-11-06 16:25:13
|
相似题推荐
解答题-问答题
|
适中
(0.65)
名校
【推荐1】已知三棱锥
中,△
与△
均为等腰直角三角形,且∠
,
,
为
上一点,且
平面
.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/19/b08670ff-197f-4e56-964e-8fed0a24bf62.png?resizew=182)
(1)
;
(2)过
作三棱锥的截面分别交
于
,若四边形
为平行四边形,求此四边形的面积
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/891579e7c231584a8e16b8eeff79888e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7bef5239ddbb0972700ce01daf9ee7cf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ca67a5b8f69507c8b80379e86f90a8ce.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/227e1dd092381de9c101d2a9b31c1d3f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0870247d35bf60ae14239f608da44759.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/03902478df1a55bc99703210bccab910.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/44b190c8d3d7d7d0e6e959e8a52eae90.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7abd284f76d9f5769bc189508ce2572b.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/19/b08670ff-197f-4e56-964e-8fed0a24bf62.png?resizew=182)
(1)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a77e3c1c236141d6118429fade0a9b9d.png)
(2)过
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9b81f15b049618e7077abf0968f6b63d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a7a8f3a13cb258c61e2a221c2bf09979.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/611f100dcfa7803db6eb233e2e7f2dab.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cf231f8f86fb922df4ca0c87f044cec3.png)
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解题方法
【推荐2】如图,已知四面体ABCD中,AB⊥面BCD,BC⊥CD.
![](https://img.xkw.com/dksih/QBM/editorImg/2023/1/17/72255349-24df-4216-bdaf-0c8da4acac6c.png?resizew=160)
(1)求证:
;
(2)《九章算术》中将四个面都是直角三角形的四面体称为“鳖臑”,若此“鳖臑”中,
,有一根彩带经过面ABC与面ACD,且彩带的两个端点分别固定在点B和点D处,求彩带的最小长度.
![](https://img.xkw.com/dksih/QBM/editorImg/2023/1/17/72255349-24df-4216-bdaf-0c8da4acac6c.png?resizew=160)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3bf10d92f20501e19d25f6f4159aab89.png)
(2)《九章算术》中将四个面都是直角三角形的四面体称为“鳖臑”,若此“鳖臑”中,
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ce519312a849963b376c202c3f9d7cf7.png)
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【推荐1】如图,四棱锥
的底面是边长为2的正方形,
底面
,
,
为
的中点.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/8/8/1806ce99-e75e-46c3-b489-bc2a6642469a.png?resizew=208)
(1)求异面直线
与
所成的角;
(2)在底边
上是否存在一点
,使
平面
?证明你的结论.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0585b6c0f156eecf9662b9846d4eb693.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5a1b49f64e0065edad868b25e9fcada3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/37e2267c84394668eff2e9f5918de4fb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d2be49c37e30a3ced0364c3e74d8c687.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/8/8/1806ce99-e75e-46c3-b489-bc2a6642469a.png?resizew=208)
(1)求异面直线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bd33764ff4efddfe11a98a609753715c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e6e490f703eb6c9bb1278c78ebc2d661.png)
(2)在底边
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/03902478df1a55bc99703210bccab910.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4a5f445af1ae136773cb338920552ff2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e7b7c83470489253394bd288d7c920df.png)
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解题方法
【推荐2】如图,
是半圆
的直径,
是半圆
上除
外的一个动点,
垂直于半圆
所在的平面,
,
,
,
.
![](https://img.xkw.com/dksih/QBM/2013/5/30/1571235507347456/1571235512975360/STEM/6cba6f7ec0134f1d9aeeceed9cf881e3.png?resizew=190)
(1)证明:平面
平面
;
(2)当三棱锥
体积最大时,求二面角
的余弦值.
![](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/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1dde8112e8eb968fd042418dd632759e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/01c74a907dda6bb7d9d56d009d9df253.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9e52a8f07834cbbbe4224962672fbbb2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1dde8112e8eb968fd042418dd632759e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c51e24fe600a16f681637e1e4be49213.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/960881cae7daf8b031c57e5e603e4cea.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d2c15801fee2405573677484f5dcfa4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/31087aa82ec3e292a75c634f628cff00.png)
![](https://img.xkw.com/dksih/QBM/2013/5/30/1571235507347456/1571235512975360/STEM/6cba6f7ec0134f1d9aeeceed9cf881e3.png?resizew=190)
(1)证明:平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4d28c625d7ac6878957facc8274d459c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b4eb7e9ad5486cf1c5e506b20c5469e8.png)
(2)当三棱锥
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b32fdd65aa55d1833750ef453a295d19.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f18a490a22cac27417ddc794f00a1941.png)
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【推荐3】如图,三棱锥
中,底面
是边长为2的等边三角形,
.
(1)证明:
;
(2)若
,点
为
的中点,求平面
与平面
的夹角的余弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/63397cda22cb1fad59cf966dfb588643.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7bef5239ddbb0972700ce01daf9ee7cf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1af5e8cc3b8dd8a6b69dfe0be870ca29.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2024/2/22/14755022-91f6-4312-9099-efb81f5473ff.png?resizew=128)
(1)证明:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d2ccdd87b7ea0667fb405c305c6a497a.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8825d400f453c5c17a7beeb1cc9a9cf3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d2be49c37e30a3ced0364c3e74d8c687.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4734735213b599a9915e1ed91a5d8ce4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e7b7c83470489253394bd288d7c920df.png)
您最近一年使用:0次
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解题方法
【推荐1】如图,在直角梯形
中,
,直角梯形
通过直角梯形
以直线
为轴旋转得到,且使得平面
平面
.
为线段
的中点,
为线段
上的动点
![](https://img.xkw.com/dksih/QBM/2021/12/9/2868381526171648/2870484108845056/STEM/813292a2710e4456a9ffa49024263d36.png?resizew=307)
(1)求证:![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e3a5c773af90119232d95de70286a5d2.png)
(2)当点
是线段
中点时,求二面角
的余弦值
(3)是否存在点
,使得直线
平面
?请说明理由.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e9edc50f7febbc2d5d8dcdc23a3630a7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/87e6cef92f3af6baae878c2c2a2be018.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6ac61c24f99a4e466f1e2ea011893866.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e9edc50f7febbc2d5d8dcdc23a3630a7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2777840758e70e7dbbc18cef8f3d6d2b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0671b4776e142e17a79af5b3f0378ef7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e9edc50f7febbc2d5d8dcdc23a3630a7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.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/e0a851907ada2ac2c3c4880a6736d28a.png)
![](https://img.xkw.com/dksih/QBM/2021/12/9/2868381526171648/2870484108845056/STEM/813292a2710e4456a9ffa49024263d36.png?resizew=307)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e3a5c773af90119232d95de70286a5d2.png)
(2)当点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e0a851907ada2ac2c3c4880a6736d28a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/eb101c2c13e4ddae09dd8e805ef185dc.png)
(3)是否存在点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/07391ef575d28f09bc5cda0ff8130a54.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/faa23fa14f624ad8212bda55d321362f.png)
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【推荐2】已知直三棱柱ABC-A1B1C1中,AB=AC=AA1=1,M,N分别为A1C1,AB1的中点.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/10/25/5d1285ca-da49-4acd-8fb8-077076b47bd4.png?resizew=134)
(1)求证:MN//平面B1BCC1;
(2)若P是B1B的中点,AP⊥MN,求二面角A1-PN-M的余弦值.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/10/25/5d1285ca-da49-4acd-8fb8-077076b47bd4.png?resizew=134)
(1)求证:MN//平面B1BCC1;
(2)若P是B1B的中点,AP⊥MN,求二面角A1-PN-M的余弦值.
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