Answer
$9$
Work Step by Step
As period of tangent function is $\pi$, then
$\tan \theta=\tan(\theta+\pi)=\tan(\theta+2\pi)$
Hence,
$$\tan\theta+\tan(\theta+\pi)+\tan(\theta+2\pi)=\tan{\theta}+\tan{\theta}+\tan{\theta}=3\tan\theta=3\times3=9$$