Find the radius of the circle with equation x^2 - 4x + y^2 - 6y - 36 = 14x + 2y
x^2 - 4x + y^2 - 6y - 36 = 14x + 2y simplfy
x^2 -18x + y^2 -8y = 36 'complete the square' for x and y
(x-9)^2 + (y-4)^2 = 36 + 81 + 16
= 133 = r^2 r = sqrt (133)