Consider a circle in the coordinate plane. The center of circle C is (h,k). Consider any point D(x,y) on the circumference of the circle. Let r represent the radius of the circle as shown in the figure.

A circle with center C is at point (h, k) is drawn on a coordinate plane. A point D is on circumference at point (x, y). Radius r connects center C to point D. The circumference of circle intersects the X-axis at two points and Y-axis at two points.

Based on the given figure, complete the table to derive the equation of a circle in standard form.