# The Trammel of Archimedes

The Trammel of Archimedes

This Demonstration shows the construction of an ellipse using a rod fixed to two green points on the brown cross. As you elongate the ellipse, the size of the cross required changes accordingly. When the cross disappears (at ), the two green points coincide and a circle is produced.

a=1

The parametric equations for the ellipse are ,

x=asin(t)

y=cos(t).