An ellipse obtained as the intersection of a cone with a plane.

An ellipse is a shape that looks like an oval or a flattened circle.

In geometry, an ellipse is a plane curve which results from the intersection of a cone by a plane in a way that produces a closed curve.

Circles are special cases of ellipses, created when the cutting plane is perpendicular to the cone's axis.

An ellipse and its properties.

The foci (purple crosses) are at intersects of the major axis (red) and a circle (cyan) of radius equal to the semi-major axis (blue), centred on an end of the minor axis (grey)

A circle has one center, called a focus. An ellipse has two foci.