parametric eqns for x^2 + y^2 = 4 in 3rd quadrant

[btrfly24]

I can't figure out where to even start on this one:

Write a pair of parametric equations that will produce that portion of the circle x^2 + y^2 = 4 that lies in the third quadrant.

Please help point me in the right direction! Thanks.

 

[pka]

\(\displaystyle \L \begin{array}{lr}
{\left\{ {\begin{array}{lr}
{x(t) = 2\cos (t)} \\
{y(t) = 2\sin (t)} \\
\end{array}} \right.} & {, \pi \le t \le \frac{{3\pi }}{2}} \\
\end{array}\)