A quantity defined for a conic section which can be given in terms of semimajor a and semiminor axes b.

The eccentricity can also be interpreted as the fraction of the distance along the semimajor axis at which the focus lies,


where c is the distance from the center of the conic section to the focus.

See also

Circle, Conic Section, Eccentric Anomaly, Ellipse, Flattening, Focal Parameter, Focus, Graph Eccentricity, Hyperbola, Parabola, Semimajor Axis, Semiminor Axis

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Cite this as:

Weisstein, Eric W. "Eccentricity." From MathWorld--A Wolfram Web Resource.

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