※ 引述《ChenYM (老宅男一個)》之銘言:
: https://i.imgur.com/Vp9FvGk.jpg
: 請教前輩這一題
: 是用參數式嗎?
A(2 + cost, sint),B(-4 - sint, cost)
C(-1 + (cost - sint)/2, (sint + cost)/2)
AB^2 = [6 + (cost + sint)]^2 + (sint - cost)^2
= 36 + 12(cost + sint) + (cost + sint)^2 + (sint - cost)^2
= 36 + 12(cost + sint) + 2
= 36
=> (cost + sint) = -1/6
題目要求 = |(sint + cost)/2| = 1/12
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