To calculate the integral of $\displaystyle ydx+(x^2+y^2)dy$ over the curve $\displaystyle y=\sqrt{4-x^2}$ between (-2,0) and (2,0), can I parameterize the curve to $\displaystyle x=2\cos t$, $\displaystyle y=2\sin t$, $\displaystyle \pi \leq t \leq 2\pi$?