# Eccentricity

*Eccentricity: how much a conic section (a circle, ellipse, parabola or hyperbola) varies from being circular.*

A circle has an **eccentricity of zero**, so the eccentricity shows you how "un-circular" the curve is. Bigger eccentricities are less curved.

Different values of eccentricity make different curves:

- At
**eccentricity**= 0 we get a circle - for 0 <
**eccentricity**< 1 we get an ellipse - for
**eccentricity**= 1 we get a parabola - for
**eccentricity**> 1 we get a hyperbola - for infinite
**eccentricity**we get a line

Eccentricity is often shown as the letter e (don't confuse this with Euler's number "e", they are totally different)

## Animation

Try the slider to see what happens:

## Calculating The Value

For a circle, eccentricity is 0 | |

For an ellipse, eccentricity is: | |

For a parabola, eccentricity is 1 | |

For a hyperbola, eccentricity is: |