Wolfram Demonstrations Projecthttp://demonstrations.wolfram.com/An Open Resource of Interactive Mathematica VisualizationsCopyright 2009 Wolfram Demonstrations Project & ContributorsInterior and Exterior Angles of Regular Polygonshttp://demonstrations.wolfram.com/InteriorAndExteriorAnglesOfRegularPolygons/]]>http://demonstrations.wolfram.com/InteriorAndExteriorAnglesOfRegularPolygons/