2x kuadrat+2y kuadrat-12x-20y=12

titik pusat (a,b) = (3,5)
x^2+y^2-6x-10y=6
titik pusat (a) = -6/-2 = 3
titik pusat (b) = -10/-2 = 5
(x-3)^2 + (y-5)^2 = r^2
x^2-6x+9+y^2-10y+25=r^2
(x^2+y^2-6x-10y)+9+25=r^2
6+9+25=r^2
r^2 = 40
r=2 akar 10