原帖由 ehbb 於 2020-11-3 06:28 PM 發表
known:
1. DE = FG = k
2. AC = 5 (pyth thm)
3. shortest distance from B to AC
thus height of triangle BDG = (a) - k
let DG = EF = y, Area of DEFG = ky
let AE = x, then FC = 5-x-y
AND, Area D ...
原帖由 rchan626 於 2020-11-3 09:59 PM 發表
我既計法都係用相同扣減方法, 計到大約淨下 [12-5k+y(2k-2.4)]/2 就停左, 無辦法變到問題所問既 (5k/12)(12-5k).
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