如图,
平面
,
,
,
,
,
是
的中点.
![](https://img.xkw.com/dksih/QBM/2019/7/16/2247931161116672/2247957236981760/STEM/1791813d9e1b427c94cd33e68c37cc82.png?resizew=235)
(1)求证:
平面
;
(2)求二面角
的余弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fc77e828650bc522b229a9d11e0197c1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f01fb34062af96f8ba7e1e05fb5f862.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/24914bb2ddc7a5d0cb8772ea5fd31401.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4b4568a33b56a5683c5bd4ff3a05fb32.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5e61dcea246d9be228d26796f59443bc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/252053b853152bd294a8315debd00b92.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d2be49c37e30a3ced0364c3e74d8c687.png)
![](https://img.xkw.com/dksih/QBM/2019/7/16/2247931161116672/2247957236981760/STEM/1791813d9e1b427c94cd33e68c37cc82.png?resizew=235)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b69c2344dc6a9f77a169f2b320263418.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e7b7c83470489253394bd288d7c920df.png)
(2)求二面角
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c0fa442c18f1129caf84cb6ff4425fe4.png)
更新时间:2018-10-21 16:28:34
|
【知识点】 面面角的向量求法
相似题推荐
解答题-证明题
|
较难
(0.4)
名校
【推荐1】如图,三棱锥
的平面展开图中,
,
,
,
,
为
的中点.
![](https://img.xkw.com/dksih/QBM/editorImg/2024/1/19/18c0a231-9066-4003-8e38-a35b7d141e94.png?resizew=339)
(1)在三棱锥
中,证明:
;
(2)求平面
与平面
夹角的余弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/63397cda22cb1fad59cf966dfb588643.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/080db3af81b29ed10144a1c2e2a4fb8a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d7db30a899f7d89f6eff964707040535.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/617c26a399344071755083c4a3bdee32.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/033e498669f796677374096e59f82a72.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d3de68627f7f3d7f81b61bf743f311ea.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2024/1/19/18c0a231-9066-4003-8e38-a35b7d141e94.png?resizew=339)
(1)在三棱锥
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/63397cda22cb1fad59cf966dfb588643.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d320f180419175d75eebc618cc458b39.png)
(2)求平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e7b7c83470489253394bd288d7c920df.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7bef5239ddbb0972700ce01daf9ee7cf.png)
您最近一年使用:0次
解答题-问答题
|
较难
(0.4)
解题方法
【推荐2】如图,将等腰直角
沿斜边
旋转,使得
到达
的位置,且
.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/7/b700e49f-33b5-46cf-8904-120b3bf6d21b.png?resizew=157)
(1)证明:平面
平面
.
(2)求二面角
的余弦值.
(3)若在棱
上存在点
,使得
,
,在棱
上存在点
,使得
,且
,求
的取值范围.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.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/3953cec61ac602ce5eb59b7912352179.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f90f9fba63790e1e5308fa5a1441d71a.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/7/b700e49f-33b5-46cf-8904-120b3bf6d21b.png?resizew=157)
(1)证明:平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ae50ff4c814b581a78346e548964aae7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7bef5239ddbb0972700ce01daf9ee7cf.png)
(2)求二面角
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/00f1eaa084baa5272450c34ab1ffde54.png)
(3)若在棱
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7ffb952f86442845da723fd291564484.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bb1a61e889d0b83ed95a38f1adf4e8e7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/077ad2164c272a0ca4c52f3159b0e486.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6655cc150ddc9deba2254780984d0024.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/54a5d7d3b6b63fe5c24c3907b7a8eaa3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f5987b311288bb1f71556dfe81d936c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/79498e1df1280868532f59ee8059a223.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/df64046e91b047037f19e4032e3b6de3.png)
您最近一年使用:0次