Use Reference Angles to Find the Exact Value of the Expression

Multiple Choice

Use reference angles to find the exact value of the expression. Do not use a calculator.
- $\tan \frac { 91 \pi } { 6 }$

A) $\frac { \sqrt { 3 } } { 3 }$
B) $- \frac { \sqrt { 3 } } { 3 }$
C) $\sqrt { 3 }$
D) $- \sqrt { 3 }$