A plane through a right angle cone. The circle is a special case of the ellipse, an ellipse with an eccentricity of zero.
- The equation of an ellipse is given by
- This may be approximated as
The eccentricity e of an ellipse can be computed by the formula:
where: a is the semimajor axis and b is the semiminor axis.
The ratio of the distance between the center and focus of an ellipse to its semimajor axis.