Answer
(a) $150 ^o$
(b) $-20 ^o$
(c) $-240 ^o$
(d) $229 ^o$
Work Step by Step
To convert radians to degrees, multiply by $\frac{180}{\pi}$
(a) $$\frac{5\pi}{6} \times \frac{180}{\pi} = 150^o$$
(b) $$-\frac{\pi}{9} \times \frac{180}{\pi} = -20^o$$
(c) $$-\frac{4\pi}{3} \times \frac{180}{\pi} = -240^o$$
(d) $$4 \times \frac{180}{\pi} = \frac{720^o}{\pi} \approx 229^o$$
