The Trammel of Archimedes

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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.


The parametric equations for the ellipse are ,


Contributed by: Jamie Wickham-Jones (March 2011)
Open content licensed under CC BY-NC-SA



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