YLL討論網

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Anonymous 寫到:

(令半徑=1)
1. 圓周角θ 對應的弦長為 2sin(θ)
2. 正方形對角線AC是直徑
3. 角ABP = 角ACP = α, AP = 2 sin(α)
4. 角CBP = 90º-α, CP = 2 sin(90º-α)
5. 角BCP = 45º+α, BP = 2 sin(45º+ α)
6. AP + CP = 2 sin(α) + 2sin(90º-α) = (2√2) sin(45º+α)
7. (AP+CP)/(BP) = √2