1 . 如图,ABCD与ADEF是两个边长为1的正方形,它们所在的平面互相垂直.
![](https://img.xkw.com/dksih/QBM/2021/11/21/2856054245351424/2856972157730816/STEM/75c868fe-c28c-46ff-a23d-ccb61c6c2430.png?resizew=219)
(1)求异面直线AE与BD所成角的大小;
(2)在线段BD上取点M,在线段AE上取点N,且
,
,试用x,y来表示线段MN的长度;
(3)在(2)的条件下,求MN长度的最小值,并判断当MN最短时,MN是否是异面直线AE与BD的公垂线段?
![](https://img.xkw.com/dksih/QBM/2021/11/21/2856054245351424/2856972157730816/STEM/75c868fe-c28c-46ff-a23d-ccb61c6c2430.png?resizew=219)
(1)求异面直线AE与BD所成角的大小;
(2)在线段BD上取点M,在线段AE上取点N,且
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/da39d66009576e7d0d664d1faee3e389.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cea8fb90cd939a5495d572c9628df968.png)
(3)在(2)的条件下,求MN长度的最小值,并判断当MN最短时,MN是否是异面直线AE与BD的公垂线段?
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解题方法
2 . 已知点A为圆台
下底面圆
上的一点,S为上底面圆
上一点,且
,
,
,则下列说法正确的有( )
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6e65ac334119ccd6204402a7aba29a55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3c4f6f74444b2b7947fc6e35c8d62322.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/23f919bd3dde10dbbc076f7ec5149699.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/31af799fd63896b640e833d617393480.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c8e1f1a8f8efc198f933a0fe28f487f8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/daf61b2c905d1eefe4198d43e8803cef.png)
A.直线SA与直线![]() ![]() |
B.直线SA与直线![]() ![]() |
C.圆台存在内切球,且半径为![]() |
D.直线![]() ![]() ![]() |
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