# Ellipse: Definition

- Author:
- Brian Sterr

- Topic:
- Ellipse

In the diagram, below, we have two given points, and . The distances from these two points to a point , given by and always add up to the same amount.

**Definition of an Ellipse:**The set of all points, the sum of whose distances to two fixed points is a constant.Questions to Consider

- What happens if you slide the value of
? How does it affect the graph? Does it change the sum ? - What happens if you slide the value of
? How does this affect the graph? Does it affect ? - Can you adjust
and so that the figure is a circle? - What happens if
?