Ellipse Calculator

A closed plane curve resulting from the intersection of a circular cone and a plane cutting completely through it. Note: "the sums of the distances from the foci to any point on an ellipse is constant." Since the distance between the two foci remain constant, the loop length is given so one can tie a string and tie a loop, put it around the two foci, and a pencil point, tautly held will trace the ellipse,