An ellipse is a set of all points on a plane where the sum of the distances from any two fixed points is constant. These points are called the foci.

Figure 1. |
---|

Above, we have an ellipse with its vertex at (0, 0).

An ellipse has a major axis and a minor axis, which intersect in the center.

Figure 2. |
---|

Equation of an Ellipse |
---|

The equation for an ellipse depends on if it is horizontal or vertical (as determined by its major axis). |

Figure 3. |
---|

Above, an ellipse is graphed next to its equation.