Recall that an equation of a circle can be written in the form , where (h, k) is the center and r is the radius. Expanding terms, the equation can also be written in the form x + y + Ax + By + C = 0. a . Find an equation of the form x + y + Ax + By + C = 0 that represents the circle that passes through the three points (4, -4), (2, -8), and (-5, -1). b. Find the center and radius of the circle.