tolong bantu ya no 6 plis

x^2 - 6x + y^2 - 8x + 16 = 0
x^2 - 6x + ... + y^2 - 8y + 16 = 0 + ...
x^2 - 6x + 9 + y^2 - 8y + 16 = 0 + 9
(x - 3)^2 + (y - 4)^2 = 9
(x - p)^2 + (y - q)^2 = r^2
p = 3
q = 4
r^2 = 9 => r = ± 3 => r = 3 atau r = -3