Hey guys, just having a bit of trouble getting started with this.

Have to use a change of variables to evaluate the integral

$\displaystyle \int\int_{D}sin(x+2y)sin(3x-y)dxdy$

where $\displaystyle D={ (x,y)\in\Re^2 | 0 \leq x+2y \leq (\Pi/2) and 0\leq 3x-y\leq (\Pi/2) }$

I assume we use polar coordinates, I'm just a bit lost with the inequalities in D