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[几何] 来自人教群的切正四面体为两全等

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kuing posted 2015-5-9 03:23 |Read mode
辽B爱好者1bk3(2047******) 19:48:55
用一个平面去截正四面体,使它成为形状,大小都相同的两个几何体,则这样的平面的个数有多少个? 答案:无数个

想不明白

粤A爱好者kuing✈(249533164) 19:50:47
如果没记错的话,过对棱中点连线的平面都符合

[中间省略一堆]

粤A爱好者kuing✈(249533164) 20:20:22
或者这么说,记正四面体对棱中点连线为L,由于正四面体以及过L的任意平面绕L旋转180度后都与原先重合,所以必然全等

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