如图,三棱锥
的侧面
是等腰直角三角形,
,
,
,且
.
![](https://img.xkw.com/dksih/QBM/2018/11/1/2066236404359168/2069122310815744/STEM/ca923945c1d44e36a731f511d470d5c1.png?resizew=165)
(1)求证:平面
平面
;
(2)求二面角
的余弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/891579e7c231584a8e16b8eeff79888e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ab2a2834d80ff574e79eae8ca8d4e94f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6037bba27008abc96a6dba99753549ad.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6703a78d8d161ec1b7bcd5dcfe45b22e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8691c8ea88a3eb4de93256f090e6d905.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8520a21b909d04f763d0f61dd74bc158.png)
![](https://img.xkw.com/dksih/QBM/2018/11/1/2066236404359168/2069122310815744/STEM/ca923945c1d44e36a731f511d470d5c1.png?resizew=165)
(1)求证:平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fcf6dc837ae85207789b94d109c5c2eb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ca67a5b8f69507c8b80379e86f90a8ce.png)
(2)求二面角
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9c909cd1b6f3fa1ec39eb245e8f5c11c.png)
更新时间:2018-11-05 18:23:01
|
相似题推荐
解答题-问答题
|
适中
(0.65)
【推荐1】如图,四棱台
的上、下底面均为菱形,
平面
![](https://img.xkw.com/dksih/QBM/2021/5/14/2721030608551936/2723084092465152/STEM/daf0b8d3-77e7-4821-a7a3-0f8e2f0b8b13.png?resizew=229)
(1)证明:平面
平面
;
(2)求四棱台
的体积
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6e09725691ee7851f54c0dee86b2bf55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8a8bfe2553e852df73185d017c0a62fb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/095c2f638e5cce918769ca0f7c765b04.png)
![](https://img.xkw.com/dksih/QBM/2021/5/14/2721030608551936/2723084092465152/STEM/daf0b8d3-77e7-4821-a7a3-0f8e2f0b8b13.png?resizew=229)
(1)证明:平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0fc4556d2b9a3395c624730c253b7db.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bfb3f0b5d8bf98eeff66f43b7dcbb4be.png)
(2)求四棱台
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6e09725691ee7851f54c0dee86b2bf55.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】在四棱锥
中,
为正三角形,平面
平面
,E为
的中点,
,
,
.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/10/3514e66e-9f4c-4506-aaaf-0959a1fa5773.png?resizew=195)
(Ⅰ)求证:平面
平面
;
(Ⅱ)求直线
与平面
所成角的正弦值;
(Ⅲ)在棱
上是否存在点M,使得
平面
?若存在,求出
的值;若不存在,说明理由.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0585b6c0f156eecf9662b9846d4eb693.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/55a675310c8ba418e5a59beb7317e21e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/93edc7bb513f40a89173121c8570cd65.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/03902478df1a55bc99703210bccab910.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/10df84d553a8826a7ce9bff4bf0d95b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1134c8e3440abb6cd385af2c169037fe.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d43dfede0d7e17c2ad89ab51349e6bf0.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/10/3514e66e-9f4c-4506-aaaf-0959a1fa5773.png?resizew=195)
(Ⅰ)求证:平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/342d452a7b850cd3a15b23619ad39bd7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/852aabd89edffc1b94344ff3f1f31ccd.png)
(Ⅱ)求直线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d2be49c37e30a3ced0364c3e74d8c687.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/80f747eb5b2d21c9de962cbfd4ec4bb7.png)
(Ⅲ)在棱
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7d0edb1508fc95765f3bb316bcb5252d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/64eb31601464364be2baf4aa87404bcd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/702fd8a01ce539178dd1f3aba60c59b2.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1】如图,直四棱柱
中,
是等边三角形,![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1134c8e3440abb6cd385af2c169037fe.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/3/16/c9c1d8f8-4b0c-4dd3-88f0-c2d96f52011a.png?resizew=166)
(1)从三个条件:①
;②
;③
中任选一个作为已知条件,证明:
;
(2)在(1)的前提下,若
,
是棱
的中点,求平面
与平面
所成角的余弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6e09725691ee7851f54c0dee86b2bf55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1134c8e3440abb6cd385af2c169037fe.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/3/16/c9c1d8f8-4b0c-4dd3-88f0-c2d96f52011a.png?resizew=166)
(1)从三个条件:①
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cfc1f76257275ab4b04f9bc913535670.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f7dbf31dfd36aa456a63bafea8bc1985.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c2d6ceed6e5a36193bcb5a557853dbee.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6d1aa6737e2a2695bb3cdb2a61a65f06.png)
(2)在(1)的前提下,若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ccc2009ab276186489f2b86e0e4c9e8c.png)
![](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/6b97d75d0594122ee2d53a67bf427d97.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d8d9157c84e0b2c946b0b65c8087e3f.png)
您最近一年使用:0次
解答题-证明题
|
适中
(0.65)
名校
【推荐2】如图所示,半圆柱的轴截面为平面
,
是圆柱底面的直径,
为底面圆心,
为一条母线,
为
的中点,且
.
;
(2)求平面
与平面
夹角的余弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e168672b47d7e64dc1b404f8882c7dcf.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/2777840758e70e7dbbc18cef8f3d6d2b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d88bf46ad08f9677c37eed1d0369329.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e07956720a50ff238c0766a5d58d00e2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e346722774c2a1913719928e352d78ef.png)
(2)求平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/69bcb3226e013650b7d8827c31dd41d0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4fa768881697b8d4c246b511b63e134c.png)
您最近一年使用:0次