[tex]tan(\theta )=\sqrt{3}\implies tan(\theta )=\cfrac{\sqrt{3}}{1}\implies tan(\theta )=\cfrac{\sqrt{3}}{1}\cdot \cfrac{2}{2} \implies tan(\theta )=\cfrac{\sqrt{3}}{2}\cdot \cfrac{2}{1} \\\\\\ tan(\theta )=\cfrac{~~\stackrel{sin(\theta )}{\frac{\sqrt{3}}{2}} ~~}{\underset{cos(\theta )}{\frac{1}{2}}}\implies \theta =tan^{-1}\left( \cfrac{~~\frac{\sqrt{3}}{2} ~~}{\frac{1}{2}} \right)\implies \theta = \begin{cases} \stackrel{I~Quadrant}{60^o}\\\\ \stackrel{III~Quadrant}{240^o} \end{cases}[/tex]
Check the picture below.
