The trammel of Archimedes

Ensino Médio::MatemáticaEducação Superior::Ciências Exatas e da Terra::MatemáticaThis 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 a=1), the two green points coincide and a circle is produced. The parametric equations for the ellipse are x=a sin(t), y= cos(t