time to get your Unit Circle, if you don't have one, this will be a good time to get one, you can get many online.
[tex]cos(x)=\cfrac{sin(30^o)}{tan(30^o)}\implies cos(x)=\cfrac{~~ \frac{1}{2}~~}{\frac{1}{\sqrt{3}}}\implies cos(x)=\cfrac{1}{2}\cdot \cfrac{\sqrt{3}}{1} \\\\\\ cos(x)=\cfrac{\sqrt{3}}{2}\implies \measuredangle x=cos^{-1}\left( \cfrac{\sqrt{3}}{2} \right)\implies \measuredangle x=30^o[/tex]
