Circle

On this diagram of a circle, the "O" its the focus, at its centre, while points "A" and "B" lie on its circumference. A line from "A" and "B" is this circle's diameter.

The four conical scones in this picture have each had a different slice through them, so they illustrate, the four different kinds of conic section, from left to right, the circle, the ellipse, the parabola and the hyperbola.

In mathematics a circle is a two-dimensional shape where the edge, or circumference, remains equidistant from the center, or focus.

A circle is a conic section, like ellipses, the parabola, and hyperbolas.