如图,在四棱锥
中,
底面
,
,
,
.
(1)若
是
的中点,求证:
平面
;
(2)
、
是棱
的两个三等分点,求证:
平面
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a8e7cedc39297d66dbb177f2a1f6bee2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ca5dd496ee0c1170ef6dcc48266ee444.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/65c42bce098904b241986bb91c65ab33.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/21b405cbf01e3a08880eebe4af89da2d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/702fa2977bc6f25103657d8af470b747.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8c4b798f9bb5482f0a3cfa1bfd77d245.png)
(1)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/03902478df1a55bc99703210bccab910.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/06222ee533c2484ab25321a6abbf98cb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7bef5239ddbb0972700ce01daf9ee7cf.png)
(2)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/54a5d7d3b6b63fe5c24c3907b7a8eaa3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/53569e6ec795658b4fffcddeebe0f142.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/192cbe130dd9ddbe4bfcf56d51450936.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/9/7/3b5bffd1-31c5-40b9-afb1-e5faacbb079c.png?resizew=161)
更新时间:2017-03-24 18:35:09
|
相似题推荐
解答题-证明题
|
适中
(0.65)
【推荐1】如图,已知
为空间的
个点,且
,
,
,
,
,
,
.
![](https://img.xkw.com/dksih/QBM/editorImg/2023/3/20/86839671-900e-4be5-9b53-7322241dfc80.png?resizew=138)
(1)求证:
四点共面,
四点共面;
(2)求证:平面
平面
;
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/835a42aed01fa3cbce897f9ce23227ff.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e8d02ea8c4988c5c28ab93f0d70fb55a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/82e093583d7113de72cc263b6b96ff3c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f396a1b68fd7c38a9002aba355c9c05e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ed5a52c6b491bc8cc7b56083f9a755ce.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a2c2ef38a7acb8b1e50c581bc9330401.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/eeb57de13c584f341fa67a829e431a91.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f2c80c26a794a844127aae7dee87c93b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0baedc4d7e690ab3f7d80d30ba0a9efe.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/3/20/86839671-900e-4be5-9b53-7322241dfc80.png?resizew=138)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0c82a10b4f0c9323d726804c89dd9548.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/42c2d86d8daea5e652d99fe1c6bc3f9a.png)
(2)求证:平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/04de6e3d84ddf7da3dc4fab26e59df46.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/aea384826175316e3c89f68abd8e2ee1.png)
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解答题-问答题
|
适中
(0.65)
【推荐2】三棱柱
中,已知
,
,点
在底面
的射影是线段
的中点
,点
在侧棱
上(点
不与点
重合).
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/24/f1303ea8-5345-419f-b2bc-35369b58bb8d.png?resizew=182)
(1)若
,证明:
平面![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3636b407d8818e15891e18db47fa0c9e.png)
(2)点
在何处时可使平面
与平面
所成的角
最小?求出此时
的值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/71f2185273bf04c11118c7954f7ec822.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1597522607f71fe3aee2f0df7c73940d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e65a3e478bb87d094e3a0af30dd10ae8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e7c314398e26ffc7164b82946eeb4273.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7bef5239ddbb0972700ce01daf9ee7cf.png)
![](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/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6024fd4532f5f981deac4582c799a6ef.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/24/f1303ea8-5345-419f-b2bc-35369b58bb8d.png?resizew=182)
(1)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/43e84aa689839e7a29978fc2f237862e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c4610344fed3177e36cdf9cdf11e81e4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3636b407d8818e15891e18db47fa0c9e.png)
(2)点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a8257b6bd25104e07b9ad935c0a3aac4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3bc6f7995516f47ebf0b3ea937c203cc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c24095e409b025db711f14be783a406c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/43660b1543b3a2b46185f7629d28a963.png)
您最近一年使用:0次
解答题-证明题
|
适中
(0.65)
名校
【推荐1】离散曲率是刻画空间弯曲性的重要指标.设
为多面体
的一个顶点,定义多面体
在点
处的离散曲率为
,其中
(
,2,…,
,
)为多面体
的所有与点
相邻的顶点,且平面
,平面
,…,平面
和平面
为多面体
的所有以
为公共点的面.
在各个顶点处的离散曲率的和;
(2)如图,现已知在直四棱柱
中,底面
是菱形,
,
①若四面体
在点
处的离散曲率为
,证明:
平面
;
②若直四棱柱
在顶点
处的离散曲率为
,求直线
与平面
所成角的正弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4bcd8ee2d8367c167d6ae0abc741b6b8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4bcd8ee2d8367c167d6ae0abc741b6b8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6f37f9a3a3b45720499a9cd2092ad467.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e1fc903da7487dcd2f069b50a5cf2bd5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7c45176df950dfe48b8ca7eac08ee349.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f0a532e15e232cb4b99a8d4d07c89575.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/835c74bbb8c61dd2d2f008664a8c8810.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4bcd8ee2d8367c167d6ae0abc741b6b8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/183f3fdb3204864ff2f60c8c1dac2f2a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/db59863ffec5fa450ab8342fd8675c2e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a9d7f18c3c9dae7e6d4f2e96281289f6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f733e19f18ab01a3c022331805ed58a6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4bcd8ee2d8367c167d6ae0abc741b6b8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/faeb97acf19bd3b2c6c77c2814df4d2f.png)
(2)如图,现已知在直四棱柱
![](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/eeed487430a5b8a330f2d0c52166521a.png)
①若四面体
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e7bdd603c88ddd439925239ac74d5461.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a18722354086c42e62334983fc50eb6a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8cc0f4e88a98b2b25320e4bed691342b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d1d2e0f281222a5f289ea4008370aed.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7935fe3125f247b7bea4f065ce9ad985.png)
②若直四棱柱
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6e09725691ee7851f54c0dee86b2bf55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4dac452fbb5ef6dd653e7fbbef639484.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0d8772aa893a9c1d40f714cb25701701.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9c2e84d6e368f8368f8301c4cd66d6dd.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,在直三棱柱
中,
,
,点
是
的中点.
平面
;
(2)求证:
平行于平面
;
(3)问线段
上是否存在点
,使得
平面
?
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/42d3a82b8e587ee890467835bc4e854c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/836454922ab97fd8e2603eb05d19eed4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/615fc8790237a1b09af51d6bcad6b595.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/97f30533da2e1d2a958dc906c37eba9d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b9b7b7793d29d66dfdd89e7a6564a35c.png)
(2)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8de4061493641220e120c78902f00de4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cbc7e774e4ae40c23bf4ceed179230ca.png)
(3)问线段
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4f36f074d1dc1054c679236ec70dcaf2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cbc7e774e4ae40c23bf4ceed179230ca.png)
您最近一年使用:0次