## Ellipse Definition

An ellipse is the set of all points which moves in a plane in such a way that the addition of its distance from two fixed points in the plane is a constant.

The two fixed points are called the foci of the ellipse.

In the given figure, F_{1} and F_{2} are two fixed points and P is a points which moves in such a way that

PF_{1 }+ PF_{2 }= **constant**.

## Major and Minor Axes

The line segment through the foci of the ellipse is the endpoint on the ellipse. This is called its** major axis**.

In the given figure , AB is the major axes of the ellipse.

**Length of the major axis = AB =2a.**

**Minor Axis**

The line segment through the center and perpendicular of the major axis with its endpoint of the ellipse. This is called its minor axis.

In the given figure, CD is the minor axis of the ellipse.

**Length of the Minor axis =CD =2b.**

## Eccentricity of the Ellipse

Since for an ellipse, c ≤ a the eccentricity is always > 1.

## Standard Equation of Ellipse

where a and b are the length of the semi-major axis and the semi-minor axis and a < b.