# Foci of an ellipse

2 videos

4 skills

Learn about the foci of an ellipse, which are two points for which the sum of the distances from any point on the ellipse is constant.

### Finding the foci of an ellipse using an interactive widget (example)

VIDEO
6:27 minutes

Sal is given an ellipse within a special interactive widget, that shows the sum of distances of each point on the ellipse from the potential foci. He uses this widget to find the exact location of the foci.

### Find the foci of an ellipse from its graph

PRACTICE PROBLEMS

Given the graph of an ellipse, use our special widget in order to determine its foci.

### Finding the foci of an ellipse from its equation

VIDEO
13:49 minutes

Sal explains how the radii and the foci of an ellipse relate to each other, and how we can use this relationship in order to find the foci from the equation of an ellipse.

### Find the foci of an ellipse from its radii

PRACTICE PROBLEMS

Given the major and minor radii of an ellipse, find its foci.

### Find the foci of an ellipse from its equation

PRACTICE PROBLEMS

Given the equation of an ellipse, find its foci.

### Write the equation of an ellipse from its foci and other features

PRACTICE PROBLEMS

Given the foci of an ellipse (and some other feature), find its equation.