# Ellipse An ellipse is set of points with a constant sum of distances to the ellipses's two focal points. A [[Circle]] can be thought of as a special kind of an ellipse, one whose two focal points are the same. The eccentricity of an ellipse describes how elongated the ellipse is, in other words the distance between the two focal points. The eccentricity of a [[Circle]]'s is 0. An ellipse is a [[Conic Section]] produced when intersecting a cone with a plane that intercepts the cone's center line, but is neither perpendicular to it (if it is perpendicular then the shape is a [[Circle]]), nor parallel to a line on the cone's surface (in which case a [[Quadratics|Parabola]] is formed). An ellipse can be defined algebraically as a set of points that satisfy the following equation: $ \frac{(x-n)^2}{a^2} + \frac{(x-m)^2}{b^2} = 1 $ Where point $(n,m)$ is the center point of the ellipse and $a$ and $b$ are the lengths of the two axes of the ellipse. When $a=b$, we're dealing with a [[Circle]].