titik pusat lingkaran x^2 + y^2 - 4x + 6y - 10 = 0 adalah

maka:
a=  -4, b=6, c=-10
p = (-1/2 (a)), (-1/2(b))
p= (-1/2(-4)), (-1/2(6))
p= 1,-3

r= √1/4(a)²+1/4(b)²-c
r= √1/4(-4)²+1/4(6)²-(-10)
r= √1/4(16)+1/4(36)+10
r=√4+9+10
r=√25
r=5