Circles and PiEllipses

Ellipses

An ellipse just looks almost like an “elongated circle”. In fact, you could think about it as a circle with two centers – these are called focal points. Just like every point on a circle has the same distance from its center, every point on an ellipse has the same sum of distances to its two focal points.

If you have a long string connected to two fixed points, you can draw a perfect ellipse by tracing the maximum reach of the strings:

Coming soon: Ellipses drawing interactive