第11章 11.9

(1)

$\sin\frac{1}{6}\pi = \frac{1}{2}$

(2)

$\sin\frac{7}{4}\pi = -\frac{1}{\sqrt{2}}$

(3)

$\sin\left(-\frac{2}{3}\pi\right) = -\frac{\sqrt{3}}{2}$

(4)

$\cos\frac{1}{2}\pi = 0$

(5)

$\cos\frac{7}{6}\pi = -\frac{\sqrt{3}}{2}$

(6)

$\cos\left(-\frac{1}{4}\pi\right) = \frac{1}{\sqrt{2}}$

(7)

$\tan\frac{1}{4}\pi = 1$

(8)

$\tan\frac{2}{3}\pi = -\sqrt{3}$

(9)

$\tan\left(-\frac{1}{6}\pi\right) = -\frac{1}{\sqrt{3}}$