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[几何] 摆线题

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hbghlyj Posted at 2020-7-18 21:11:09 |Read mode
QQ图片20200716201754.jpg
过P作外接圆的动切线,$A_1,A_2$在其上的投影为Q,R,过Q作$A_2A_3$垂线,过R作$A_3A_1$垂线交于S,求证:S的轨迹是$A_1A_2A_3$的斯坦纳三尖内摆线

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 Author| hbghlyj Posted at 2020-8-21 12:22:15
回复 1# hbghlyj
episodes in nineteenth and twentieth century Euclidean geometry第130页定理:外接圆上两点的连线的垂极点是它们的西摩松线的交点
令这两点无限逼近,就得到
外接圆切线的垂极点是西摩松线的瞬时旋转中心
也就是本题

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青青子衿 Posted at 2022-1-9 21:45:27
回复 2# hbghlyj
这个内摆线所围成区域的面积与三角形三边长的关系如何呢?

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 Author| hbghlyj Posted at 2023-4-26 03:05:23
青青子衿 发表于 2022-1-9 14:45
回复 2# hbghlyj
这个内摆线所围成区域的面积与三角形三边长的关系如何呢? ...
顶一下

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