The square of the distance between C(4, -5) and P(1, -2) is given by the Pythagorean theorem as
(4-1)² +(-5-(-2))² = 18
This is the square of the radius of the circle, so we can use it for r² in the formula
(x -h)² +(y -k)² = r² . . . . . . . circle of radius r and center (h, k)
Your circle has equation ...
(x -4)² +(y +5)² = 18
