Answer
$0$
Work Step by Step
We need to compute $\sin (-3 \pi)$.
The trigonometric function $\sin$ has a period of $2\pi$. Also, because sine is odd, $\sin (-x)=-\sin (x)$
Thus, we can simplify as follows:
$\sin (-3 \pi) =-\sin (3 \pi) \\ =-\sin (\pi + 2\pi) \\=- \sin (\pi) \\ =0$
