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[几何] 平面几何求线段长

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力工 posted 2022-10-5 16:36 |Read mode
Last edited by 力工 2022-10-5 16:51这是看到的一道中考题,据说深圳的填空题,这题我表示不容易。发出来,求教大佬的高招。
已知直角$\triangle ABC$中,两直角边$AB=3,BC=5$.线段$AE=2\sqrt{5},\triangle CDE$是以$CE$为斜边的等腰直角三角形,点$F$在线段$AE$上,且$\angle DBF=45\du $,求$AF$的长。(结果$\frac{3\sqrt{5}}{4}$)
QQ图片20221005163247.png

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exctttt posted 2022-10-6 08:21
果然可以旋转相似
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original poster 力工 posted 2022-10-6 17:25
大佬们,各自都来炫一个

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original poster 力工 posted 2022-10-11 13:01
看来大佬们兴趣不大,我用向量或坐标法好像也进行不了。

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original poster 力工 posted 2022-10-11 14:01
力工 发表于 2022-10-11 13:01
看来大佬们兴趣不大,我用向量或坐标法好像也进行不了。
用正余弦定理也是一头雾水。

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