Circle
A circle is the set of all points in a plane at a given distance (called the radius) from a given point (called the center.)
The equation of a circle is (x – h)2 + (y – k)2 = r2 where (h, k) is the center and r is the radius.
A circle can also be defined as a conic section obtained by the intersection of a cone with a plane perpendicular to its axis of symmetry.
