The given equation is $\cot \theta=\sqrt{3}$ which is same $\tan \theta=\frac{1}{\sqrt{3}}$.
We know that, $\tan \frac{\pi}{6}=\frac{1}{\sqrt{3}}$ and $\tan (\pi+\theta)=\tan \theta$
$\therefore \tan \frac{\pi}{6}=\tan \left(\pi+\frac{\pi}{6}\right)=\tan \frac{7 \pi}{6}$