How do I convert the following equation from polar to rectangular form?

$\displaystyle r^2 = sin\Theta$

I know $\displaystyle r^2 = x^2 + y^2$ , but I'm not sure how to eliminate $\displaystyle sin\Theta$. I know $\displaystyle rsin\Theta= y$, but multiplying both sides by r just muddies it further for me.