在直三棱柱
中,
,
,
分别为
的中点.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/28/b856458c-3f10-40d7-ae75-68245f60e3de.png?resizew=152)
(1)求证:
;
(2)求二面角
的余弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/42d3a82b8e587ee890467835bc4e854c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/36c4559d27e3905980d1a4f1856f07de.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7b9223c911c1c0ce39bc39cde160cb98.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7789a500686c7a73770404ead6af0590.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bbfb9c088a7422e95f747701a626513d.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/28/b856458c-3f10-40d7-ae75-68245f60e3de.png?resizew=152)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1c7f786fc33d0506d64047034e12fd7a.png)
(2)求二面角
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/38a0d7b8e606b160f5751a1ec5d3a92a.png)
更新时间:2018-02-28 19:36:14
|
相似题推荐
解答题-证明题
|
适中
(0.65)
名校
解题方法
【推荐1】在如图所示的多面体
中,四边形
为正方形,底面
为直角梯形,
为直角,
∥
,
.平面
平面
.
![](https://img.xkw.com/dksih/QBM/2017/3/23/1650159266144256/1650795760779264/STEM/a97cda409f414e4ab156faf9c7087285.png?resizew=189)
(1)求证:
;
(2)若
,求二面角
的余弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9165d9bfbb0f0d19eb482c2a4c1b29b7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/369eb8ad56da7dc1cdb7c43762be4bee.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d786ee723231d4ca87eb9d011a378b5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/68a83fdd2ba72a2dba0b6b10bb3e06b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/274cf35acb4a1748d15c39d15a9bea7b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3ea50a7a8ca32a3550e83483771f6fb7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4cf9a6db3571fa57bfa2d5e4d44c51b3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/369eb8ad56da7dc1cdb7c43762be4bee.png)
![](https://img.xkw.com/dksih/QBM/2017/3/23/1650159266144256/1650795760779264/STEM/a97cda409f414e4ab156faf9c7087285.png?resizew=189)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/509d8dd6031dc0ef92075877e53fe201.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/be5fc6ead6416492c231c320a5486f86.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/69856a547e733af483753a1dc51f47bf.png)
您最近一年使用:0次
解答题-证明题
|
适中
(0.65)
【推荐2】如图,在棱长为2的正方体
中,E为棱BC的中点,F为棱CD的中点.
平面
;
(II)求直线
与平面
所成角的正弦值.
(III)求二面角
的正弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6e09725691ee7851f54c0dee86b2bf55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9cf55043d616833f4a69e0386b03711b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/37fd7d2bc169d4467ad7d70861ed6351.png)
(II)求直线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/24bb49fdc6b6bbb2449fdf8a0de769d3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/37fd7d2bc169d4467ad7d70861ed6351.png)
(III)求二面角
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0515843e223f9643b73c4d34745d0d56.png)
您最近一年使用:0次
解答题-问答题
|
适中
(0.65)
【推荐1】《九章算术》是我国古代内容极为丰富的数学名著,书中将底面为直角三角形的直棱柱称为堑堵,将底面为矩形的棱台称为刍童.在如图所示的堑堵
与刍童
的组合体中
,
.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/10/28/801d7f13-23c7-4df2-8b01-82c2c53e9bcb.png?resizew=207)
(1)证明:
平面
;
(2)若
,
,
,三棱锥
的体积为
,求二面角
的余弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d762c010dbf90d25bb4b72c849db3e07.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6e09725691ee7851f54c0dee86b2bf55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2e735a28578ba191da6d4f3b0f8e8729.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/56862f9a75ba084f3ddb81aa130d5685.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/10/28/801d7f13-23c7-4df2-8b01-82c2c53e9bcb.png?resizew=207)
(1)证明:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5a5928c98b341b16d4b5a5b931d2929d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fb304d905125170bebfada27e7ed8960.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ced06b71073e1bb777f326f06016ce17.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f0b006143c991165cd8c9f6fe11831b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5a3acdab98dbc9b6c859bfe0f12d4556.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac20024c3622b78dfaa2f4ef75714dee.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/18483c9c195ecd922772527fa85c0fcb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/54d6f331f6cf759bd0cd2edbc809e875.png)
您最近一年使用:0次
解答题-证明题
|
适中
(0.65)
【推荐2】如图,在三棱柱
中,四边形
是菱形,四边形
是正方形,
,
,
,点
为
的中点.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/8/006e9251-90c9-4e5d-9e6f-3ed58bcd0e2e.png?resizew=209)
(1)求证:
平面
;
(2)求二面角
的余弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/986ba572d8373df48c996f8c8611498c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e1d70676406f26d339465fe3473c0c05.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/937b9e610b548398bc46ed29951e7f74.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/822ba132ca9dd0d4a050659aef3c9b26.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fcd0ced286a0fbc7e4862f8147264277.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f945a69cf7e8213e50622125cde652f5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/895dc3dc3a6606ff487a4c4863e18509.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/8/006e9251-90c9-4e5d-9e6f-3ed58bcd0e2e.png?resizew=209)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e9d32e76582bf550593fdef53e081225.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/af841bc357e88fac4834ea8b6b3e9207.png)
(2)求二面角
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1b0a54fd11132ff8d2aece3d053a55b1.png)
您最近一年使用:0次