me Equation Given the center and a Point on the Circle Find the equation of the circle with a center at (1,-5) that passes through the point (3,-8). 1. Use the formula to determine the radius. d = (x-x1)+(yz - y) Let (x1,y1)=(1,-5) and (x2,y2) = (3,-8) =(3-1)+(-8-(-5)) =4+ (-8+5) = 4 +9 2. Substitute the known values into the standard form. r = 13 h = (x - h) + (y - k) gi k= (x-1)+(y-(-5)) = (13) (x-1)+(y+ 5) =