We are asked to evaluate cot 120,
[tex]\begin{gathered} \cot 120^0=\frac{1}{\tan 120^0} \\ 120^0\text{ falls in the second quadrant. } \\ \tan 120^0=-\tan (180^0-120^0)=-\tan 60^0 \\ \end{gathered}[/tex][tex]\Rightarrow\cot 120^0=-\frac{1}{\tan 60^0}=-\frac{1}{\sqrt[]{3}}=-\frac{\sqrt[]{3}}{3}[/tex]
