
Related:
 Equation of Ellipse
 Major Axis of Ellipse
 Minor Axis of Ellipse
 Vertices
 Covetices
 focus of an ellipse
 Is a circle an ellipse?
 Eccentricty of Ellipse
 area of an ellipse
 Orbits of Planets as ellipses
 Translate ellipse
 images
 Worksheet Version of this Web page (same questions on a worksheet)
The eccentricity of an ellipse is a measure of how nearly circular the ellipse. Eccentricity is found by the following formula eccentricity = c/a where c is the distance from the center to the focus of the ellipse a is the distance from the center to a vertex
Formula for the Eccentricity of an Ellipse
The special case of a circle's eccentricity
A circle is a special case of an ellipse. Analogous to the fact that a square is a kind of rectangle, a circle is a special case of an ellipse. In terms of the eccentricity, a circle is an ellipse in which the eccentricity is zero.