第11章 11.4

(1)

$60° = 60° \cdot \dfrac{2\pi}{360°} = \dfrac{\pi}{3}$

(2)

$135° = 135° \cdot \dfrac{2\pi}{360°} = \dfrac{3\pi}{4}$

(3)

$270° = 270° \cdot \dfrac{2\pi}{360°} = \dfrac{3\pi}{2}$

(4)

$480° = 480° \cdot \dfrac{2\pi}{360°} = \dfrac{8\pi}{3}$