Discovery Education
Discovery Education: Web Math: Plots and Geometry
This site provides descriptions and helpful hints regarding conic sections - circles, parabolas, ellipses, and hyperbolas. Content also includes interactive problem solvers complete with a full analysis of the math behind the answer.
Discovery Education
Discovery Education: Web Math: Graphing Ellipses
WebMath offers a java applet that allows you to input information about an ellipse, in one of four forms, and gives you the graph of the ellipse.