Ellipse
Geometric figure in which the sum of the distances of each point P from two fixed points F1 and F2, called the foci, is constant.
- Consider an ellipse with foci F1 and F2 and points P1 and P2 : d(P[latex]_{1}[/latex], F[latex]_{1}[/latex]) + d(P[latex]_{1}[/latex], F[latex]_{2}[/latex]) = d(P[latex]_{2}[/latex], F[latex]_{1}[/latex]) + d(P[latex]_{2}[/latex], F[latex]_{2}[/latex])
- Segments a and b in the illustration are the semi-minor axis (conjugate axis) and the semi-major axis (transverse axis) of the ellipse. The major axis (transverse axis) is the diameter of the ellipse.
- An ellipse can also be formed by the intersection of a cone of revolution with a plane that meets all the generating lines and that does not pass through the apex.