CPM Homework Help : PC3 Problem 2-127

State all values of $0\leθ<2\pi$ that satisfy each of the following equations. Sketching a unit circle will help.

$\sin(θ)=\frac{1}{2}$
Answer (a):
$30^\circ\text{ or }\frac{\pi}{6}$
$150^\circ\text{ or }\frac{5\pi}{6}$

$\sin(θ)=−\frac{\sqrt{3}}{2}$
Hint (c):
What special angle(s) are involved?
What does the negative sign mean?