如图,在三棱锥
中,E,F,G,H分别是边AB,BC,CD,DA的中点.
(1)求证:四边形EFGH是平行四边形
(2)当AC与BD满足什么条件时,四边形EFGH是正方形.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/891579e7c231584a8e16b8eeff79888e.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/7/30/952302f9-b4e4-41e6-aafb-50a61689e7da.png?resizew=146)
(1)求证:四边形EFGH是平行四边形
(2)当AC与BD满足什么条件时,四边形EFGH是正方形.
更新时间:2023-07-29 16:59:46
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解答题-证明题
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解题方法
【推荐1】如图,在正四棱台
中,E,F,G,H分别为棱
,
,AB,BC的中点.
(1)证明E,F,G,H四点共面;
(2)证明GE,FH,
相交于一点.
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/56f7ba05c54b3de1f4378f7c8eb58328.png)
(1)证明E,F,G,H四点共面;
(2)证明GE,FH,
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e0a851907ada2ac2c3c4880a6736d28a.png)
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解答题-问答题
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(0.85)
解题方法
【推荐2】如图,在长方体
中,底面是边长为a的正方形,高为
,点M,N分别是
和
的中点.
的形状;
(2)求四边形
的面积.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b3da8c338342e38c9aa3f274c053fd5b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/878e89b6eca35e34c863e832a2c661db.png)
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(2)求四边形
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/771278f132d4cc2505e31115e2fee6d8.png)
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解答题-证明题
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较易
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【推荐1】如图,在正方体
中,E,F分别为
,
的中点,求证:平面
与平面
相交.
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cdcfe69b939fd1c271747fe9d37ccdf9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ea2f3df5713a423887c16e6355236372.png)
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解答题-作图题
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较易
(0.85)
【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
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三点的平面与平面
的交线,以及与平面
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(2)求
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6e09725691ee7851f54c0dee86b2bf55.png)
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9369aed2d8309af46ac3eaffb9cce537.png)
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/acc290b44635265137fdf13146b6a6d9.png)
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/632f2bf1cd0435041fa04b01901d1c8c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/58cc6184b191e6da43911e701121517e.png)
(2)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7a5f1641947153c80b987320885a2b57.png)
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