Johan Claeys
Math Abundance: From a Cartesian Equation to a Polar Equa
Shows how to convert a cartesian equation (rectangular coordinates) to a polar equation.
University of St. Andrews (UK)
University of St. Andrews: Parabola
This is a brief activity on the parabola. The activity also has links to related topics.
University of St. Andrews (UK)
University of St. Andrews: Ellipse
The University of St. Andrews offers a comprehensive and detailed site explaining the ellipse.