Eccentricity

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Eccentricity

(symbol e) 

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1. Of any conic, the ratio of the length of the radius vector through a point on the conic to the distance of the point from the directrix. </dd>
2. Of an ellipse, the ratio of the distance between the center and focus of an ellipse to its semimajor axis. Also called numerical eccentricity.
The eccentricity e of an ellipse can be computed by the formula

Missing Image:img src="SP7-e_files/91ecc.gif" height="20" width="101"where

a is the semimajor axis and b is the semiminor axis. </dd>
3. Of an ellipse, the distance between the center and the focus. Also called linear eccentricity. [[/a>|/a>]] </dd>

References

This article is based on NASA's Dictionary of Technical Terms for Aerospace Use