Answer
a. $30^{\circ}\rightarrow$ iii. $\frac{\pi}{6}$
b. $45^{\circ}\rightarrow$ iv. $\frac{\pi}{4}$
c. $60^{\circ}\rightarrow$ ii. $\frac{\pi}{3}$
d. $90^{\circ}\rightarrow$ i. $\frac{\pi}{2}$
Work Step by Step
$Radian\,measure=(Degree\,measure\times\frac{\pi}{180})rad$
$30^{\circ}=(30\times\frac{\pi}{180})=\frac{\pi}{6}$
Similarly,
$45^{\circ}=(45\times\frac{\pi}{180})=\frac{\pi}{4}$
$60^{\circ}=(60\times\frac{\pi}{180})=\frac{\pi}{3}$ and
$90^{\circ}=(90\times\frac{\pi}{180})=\frac{\pi}{2}$
