Answer
$0$
Work Step by Step
Recall:
(1) An angle and its reference angle either have the same trigonometric function values or differ only in signs.
(2) $\tan{\theta}=\dfrac{y}{x}$
$\pi$ is a special angle whose terminal side is the negative x-axis.
The negative x-axis intercepts the unit circle at the point $(-1, 0)$.
Therefore,
$\tan{\pi} = \dfrac{0}{-1} = 0$
