# Ellipse

- Author:
- Mark Humphries

- Topic:
- Ellipse

Create a point not on line CD. Label it E. Create an ellipse with those three points. Create a 4th point on the ellipse and label it F. Draw segment FC and segment FD. Find the length of FC and FD. Add the two lengths together. Create a text box that shows this sum. Move point F around. Find the center of the ellipse. Label what a, b, and c represent in the ellipse and find their values. Find the value of the ratio c/a.

As you move F around what do you notice about the sum of FC and FD?

What does the values (a), (b), and (c) represent in the ellipse?

What is the eccentricity of an ellipse