Eccentricity of an Ellipse

Measure of how circular Ellipse is

The eccentricy 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 Eccentricy of an Ellipse

Picture and formula eccentricity of ellipse

The special case of a circle's eccentricty

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 eccentricty, a circle is an ellipse in which the eccentricty is zero.

Practice Problems

Problem 1

Use the formula for eccentricty to determine the eccentricity of the ellipse below

Problem 2

Determine the eccentricity of the ellipse below

Problem 3

What is the eccentricity of the ellipse in the graph below?

Problem 4

Determine the eccentricity of the ellipse below?