Writing an equation of a circle given its center and radius or diameter Write an equation of the circle with center $(-4,7)$ and radius 9.

Step 1 ：The equation of a circle is given by (x - h)^2 + (y - k)^2 = r^2

Step 2 ：The center of the circle is (-4, 7) and the radius is 9

Step 3 ：Plugging these values into the equation, we get (x + 4)^2 + (y - 7)^2 = 81

Step 4 ：Therefore, the equation of the circle is (x + 4)^2 + (y - 7)^2 = 81