Double integrals in polar coordinates

Calculate \[\int_{R}\sin(x^2+y^2)\,\dd(x,y)\] where the region of integration \(R\) is the quarter circle with radius \(a\) and the origin as centre, such that \(x>0\) and \(y>0\).

\(\int_{R}\sin(x^2+y^2)\,\dd(x,y)={}\)

\(\quad\text{where }R\text{ is the given quarter circle.}\)