In mathematics, an ellipse (from Greek ἔλλειψις elleipsis, a "falling short")'s the finite or bounded case of a conic section, the geometric shape that results from cutting a circular conical or cylindrical surface with an oblique plane (the other two cases being the parabola and the hyperbola). It's also the locus of all points of the plane whose distances to two fixed points add to the same constant. Ellipses also arise as images of a circle or a sphe… (More on Ellipse)