如图,矩形
中,
,
,
为
边的中点,点
为
边上两个动点,且
,当四边形
的周长最小时,![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9985eaef9e31b243d5aaf89b71f66075.png)
__________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d2c15801fee2405573677484f5dcfa4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/07140f277a35733d8c97577ccdd4e3ab.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f6bce3d91ca23b86d8c6625f2632e437.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f4d14c6959273338a048b023805cce80.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b901190ec1f945c0e8d69b203ca153b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9985eaef9e31b243d5aaf89b71f66075.png)
![](https://img.xkw.com/dksih/QBM/2017/9/15/1774464467001344/1775818797015040/STEM/586f338c8ce54399b026cbd0408ee9f2.png?resizew=146)
更新时间:2017-09-17 08:55:30
|
【知识点】 平面的基本性质的有关计算
相似题推荐
填空题-单空题
|
较易
(0.85)
解题方法
【推荐1】在棱长为1的正方体
中,
为底面
的中心,
是棱
上一点,且
,
,
为线段
的中点,给出下列命题:
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/11/b3b303f8-4645-4fb4-aae0-da651ab57e9e.png?resizew=170)
①
四点共面;
②三棱锥
的体积与
的取值有关;
③当
时,
;
④当
时,过
三点的平面截正方体所得截面的面积为
.
其中正确的有__________ (填写序号).
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c0424446817f60c18f8e4e3cc202ad99.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/acc290b44635265137fdf13146b6a6d9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/394c5d2f55221975503be8aa18022480.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bfa920e346a3d79b7ecfa395b8e72b1f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cee72261f6901e62dfd0ffe547406544.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/54a5d7d3b6b63fe5c24c3907b7a8eaa3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/84d454c82d9e52747563d47b68099249.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/11/b3b303f8-4645-4fb4-aae0-da651ab57e9e.png?resizew=170)
①
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5ae45d5c4c2e34bf01e860748b1d22c7.png)
②三棱锥
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9933c392d85e51aba78e72468363579b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/df64046e91b047037f19e4032e3b6de3.png)
③当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/61c1eccad7857ccae05562abaaf10d25.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/558e11d700481dc414d5d073b4b88a3d.png)
④当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/73b3cf0f585938ede9eca890a6eb326d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d4aee887d79c104f7d37fafa312aef6b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7e45dbe14b2b2e3bf724be3f391b8ddf.png)
其中正确的有
您最近一年使用:0次
填空题-单空题
|
较易
(0.85)
名校
【推荐2】如图,正方体
的棱长为
分别是
的中点,设过
三点的平面与
交于点
的长为__________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6e09725691ee7851f54c0dee86b2bf55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/25d81b3c2dd9a58e4a235cbd8363b7fd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a3506756bab80cdedea9496088cc02c7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9369aed2d8309af46ac3eaffb9cce537.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/56f7ba05c54b3de1f4378f7c8eb58328.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/69b12eb4dc369e1e8565d2191d9ce193.png)
您最近一年使用:0次