解题方法
1 . 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