"(x - x0)^2 + (y - y0)^2 = r^2
So the radius is 11, half of diameter
x0 = -9
y0 = 5
so (x+9)^2 + (y-5)^2 = 11^2
(x+9)^2 + (y-5)^2 = 121
Hope that helped!"
I got this from yahoo answers: https://answers.yahoo.com/question/index?qid=20110411115016AAupcAu
