r=6+3sin(theta) convert to rectangular coordinates

r = 6 + 3sinθ

r^2 = 6r + 3rsinθ
x^2+y^2 = 6√(x^2+y^2) + 3y
x^2 + y^2 - 3y = 6√(x^2+y^2)
(x^2+y^2-3y)^2 = 36(x^2+y^2)