Polar coordinates

/sci/, what would be the best method for solving the following type of problem, "Determine whether the point lies on the curve r^2 = sin(3x) [1,-5pi/6]"

>>7
r^2 = \sin \theta \rightarrow r^3 = r \sin \theta \rightarrow \left (x^2 + y^2\right )^{\frac{3}{2}} = y \rightarrow \left (x^2 + y^2\right )^3 = y^2