Complete the equation of the circle centered at (8,−6) that passes through (8,9).

Answer 1

We are looking for an equation of the form (x-h)^2+(y-k)^2=r^2 which represents a circle of radius r centered at (h,k). Thus, since the circle is centered at (8,-6) we know that h=8 and k=-6. Next, we need to find r, but we know that the distance between (8,9) and the center of the circle at (8,-6) is 15 since they have the same x value, we know that the radius must be 15.