解题方法
1 . 已知长方体
中,底面ABCD为正方形,
,
,点
在棱
上,且
.
(1)在棱CD上确定一点E,使得直线
平面
,并写出证明过程;
(2)求证:平面
平面
;
(3)若动点F在正方形ABCD内,且
,请说明点F的轨迹,试求
长度的最小值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6e09725691ee7851f54c0dee86b2bf55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d2c15801fee2405573677484f5dcfa4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/92535536bd3c2761724fd058427f95a8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/522230546d4b802094e86ceb48c2ba38.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f66fb71b75b63594ebeeeebd1963eed5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4be266d5a7cadc5071c6cd3d9061fdee.png)
(1)在棱CD上确定一点E,使得直线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2496ad1a738d10dd97c57b7a58f852b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/263d398159c7433838b714a9a75d61e5.png)
(2)求证:平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/df00cdf77ed39ca5a0b305861a693142.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/263d398159c7433838b714a9a75d61e5.png)
(3)若动点F在正方形ABCD内,且
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bbc39144b305c67d44410d41053a1d28.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/db5108b8028b16489c9a24fbec4704c0.png)
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10-11高二下·北京·阶段练习
2 . 在长方体
中,已知底面
为正方形,
为
的中点,
,
,点
为正方形
所在平面内的一个动点,且满足
,求线段
的长度的最大值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6e09725691ee7851f54c0dee86b2bf55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/394c5d2f55221975503be8aa18022480.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/09d27bd71d79cb19eb554175e4ef0867.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6db57eca2a7cbd91bc57372592580a76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/acc290b44635265137fdf13146b6a6d9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f4a01292ba9b86837acd691c1c9384f4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cb6ede9761b5b90f8dc137708e1ee90f.png)
您最近一年使用:0次