University of St. Andrews (UK)
University of St. Andrews: Christiaan Huygens
This University of St. Andrews site contains biographical information and findings of Christiaan Huygens.
University of St. Andrews (UK)
University of St. Andrews: Involute of a Circle
This site, which is provided for by the University of St. Andrews, allows you to zoom in/out and add evolutes, involutes, etc.
University of St. Andrews (UK)
University of St. Andrews: Involute of a Circle
This site from the University of Saint Andrews shows the involute of a circle graphically and gives brief history. Cartesian equation is given.
University of St. Andrews (UK)
University of St. Andrews: Hypocycloid
Shows the graph and the parametric cartesian equation. The site also includes links to graphs of related curves and definitions of the associated curves.