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