[几何] 由外心、内心、垂心作三角形

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hbghlyj Post time 2024-3-29 08:36 |Read mode

给定3点$O,I,H$分别为$\triangle ABC$的外心、内心、垂心
于是，九点圆中心N为OH中点
由IN和OI解出R和r
现在外接、内切圆都有了，用Poncelet即可作出$\triangle ABC$：cut-the-knot.org/triangle/O-H-I.shtml

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2025-3-6 03:01 GMT+8

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