Ellipses sharing common foci (left figure). The family of confocal ellipses covers the plane simply, in the sense that there is a unique ellipse passing through each point in the plane (Hilbert and Cohn-Vossen 1999, p. 5). The figure on the right shows confocal ellipses superimposed on confocal hyperbolas, which form an orthogonal net of curves (Hilbert and Cohn-Vossen 1999, pp. 5-6).
Confocal Ellipses
See also
Confocal Conics, Confocal Hyperbolas, Confocal Parabolas, EllipseExplore with Wolfram|Alpha
References
Hilbert, D. and Cohn-Vossen, S. Geometry and the Imagination. New York: Chelsea, 1999.Referenced on Wolfram|Alpha
Confocal EllipsesCite this as:
Weisstein, Eric W. "Confocal Ellipses." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/ConfocalEllipses.html