Wolfram Demonstrations Projecthttp://demonstrations.wolfram.com/An Open Resource of Interactive Mathematica VisualizationsCopyright 2009 Wolfram Demonstrations Project & ContributorsLocus of Points Definition of an Ellipse, Hyperbola, Parabola, and Oval of Cassinihttp://demonstrations.wolfram.com/LocusOfPointsDefinitionOfAnEllipseHyperbolaParabolaAndOvalOf/]]>http://demonstrations.wolfram.com/LocusOfPointsDefinitionOfAnEllipseHyperbolaParabolaAndOvalOf/