## Precalculus (6th Edition) Blitzer

-$\frac{2\sqrt 3}{3}$
(-$\frac{1}{2}$ , -$\frac{\sqrt 3}{2}$) csc $\frac{4\pi}{3}$ is computed by $\frac{1}{y}$ So csc $\frac{4\pi}{3}$ = $\frac{1}{-\frac{\sqrt 3}{2}}$ = -$\frac{2\sqrt 3}{3}$