A conic section is the curve that results when an infinite regular cone is cut by a plane. Depending on the position of the plane, the section that results may be a Circle, a Parabola, an Ellipse or a Hyperbola. The Parabolla has one Vertex, one Focus, an Axis of Symmetry and a segment called the Latus Rectum. The Ellipse has a Center, two Vertices, two Foci, a major Axis and a Minor Axis. The Circle is a degenerate Ellipse where both Foci and the Center coincide. The Hyperbola has a Center, two Vertices, two Foci and two Asymptotes. In this video I explain the Equation of a Circle with center a t a point (h,k) and radius r, then I give you a number of exercises about the circle.