x^{2} + (y^{2} - 12y) = -20

x^{2} + (y^{2} - 12y + 36) = -20 + 36

(x - 0)^{2} + (y - 6)^{2} = 16

Center = (0,6) and radius = √16 = 4

The point (17,7) is not on the circle since substituting 17 for x and 7 for y into the equation of the circle yields a false statement.