→ Honor1984 : GH = HD = AD且HD垂直GH、AD 09/24 00:16
推 tuhunger : 漂亮唷 09/24 00:18
推 reye : 好解法 09/25 18:51
※ 引述《tuhunger (照片比本人帥)》之銘言：
: 題目如圖，感謝各位提點
: https://i.imgur.com/AaKqq7O.jpg
設FD交GE於H
CG : GA = CE : EB
=> GE // AB 且 GE = (4/5)AB
=> FD垂直AB
設AD = 2x => DB = 3x，GE = 4x，HD = 2x = GH
GH = AD且HD垂直GH、AD
=> GHDA為正方形
=> GA = HD = 2x，GC = 8x
(10x)^2 + (5x)^2 = 15^2
正方形面積 = (2x√2)^2 = 8x^2 = 72/5
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