Evaluate each of the following expressions exactly.

1. $\operatorname { tan } \frac { 2 \pi } { 3 }$ 

   Answer (a):

   $-\sqrt{3}$

2. $\operatorname { tan } \frac { 7 \pi } { 6 }$ 

   Answer (b):

   $\frac{\sqrt{3}}{3}$