Re: [中學] 求解這題
: 想很久…但沒什麼想法
: 想不到要怎麼起手破解
DE = a
AE = b
CD = h
△CDE = △AEF = △FBC
AF = ah/b
FB = ah/(a + b)
AF + FB = CD
=> [a/b + a/(a + b)]h = h
令x = b/a
=> 1/x + 1/(1 + x) = 1
=> 1 + 2x = x^2 + x
=> x = (1/2)[1 + √5]
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