請問這題等腰梯形角度求解?(OMC複試)

[Hawlee]

請問這題OCM國二複試題

[thepiano]

ABCD 是圓內接四邊形，AC 是 ∠BAD 的平分線，CD = BC = (1/2)AD
令 △AFD = x

△ACD 和 △AED 同底(AD)，面積比 = 高的比
△ACD/△AED = [(√3/2)CD]/[(√3/2)AE] = CD/AE
(x + 70)/(x + 16) = CD/AE

△AFD/△AFE = FD/FE = AD/AE (內分比定理)
x/16 = 2CD/AE
(x/2)/16 = CD/AE

(x + 70)/(x + 16) = (x/2)/16
x = 56

△AFD = 56

[Hawlee]

忽略了內分比性質，謝謝老師