Answer
$y=\frac{\pi}{6}$
Work Step by Step
RECALL:
$y=\arctan{x} \longrightarrow \tan{y}=x$, $y$ is in the interval $(-\frac{\pi}{2}, \frac{\pi}{2})$
Note that $\tan {(\frac{\pi}{6})}=\frac{\sqrt3}{3}$.
Therefore,
$y=\arctan{(\frac{\sqrt3}{3})}\longrightarrow y=\frac{\pi}{6}$
