If we slice one of the cones with a plane at right angles to the axis of the cone, the shape formed is a circle.
The circle with centre (0, 0) and radius r has the equation: x2 + y2 = r2
The circle with centre (h, k) and radius r has the equation: (x − h)2 + (y − k)2 = r2
General Form of the Circle: An equation which can be written in the following form (with constants D, E, F) represents a circle: x2 + y2 + Dx + Ey + F = 0x2 + y2 + 2gx + 2fy + c = 0Radius=√g2+f2-ccenter of Circle is given by: -g,-f