Ellipse

Ellipse

A definition of an ellipse is that it is the locus of points for which the sum of their distances from two fixed points (the foci) is constant. The smaller the distance between the foci, the more closely the ellipse resembles a circle.
A straight line drawn through the foci and extended to the curve in either direction is the major diameter (or major axis) of the ellipse. Perpendicular (at right angles) to the major axis through the centre, at the point on the major axis equidistant from the foci, is the minor axis. The ellipse is symmetrical about both its axes. [RA] {EB}