Wolfram Demonstrations Projecthttp://demonstrations.wolfram.com/An Open Resource of Interactive Mathematica VisualizationsCopyright 2009 Wolfram Demonstrations Project & ContributorsThe Interior Angles of a Triangle Sum to Pihttp://demonstrations.wolfram.com/TheInteriorAnglesOfATriangleSumToPi/]]>http://demonstrations.wolfram.com/TheInteriorAnglesOfATriangleSumToPi/A Line Crossing Two Parallel Lines Makes Alternate Angles Equalhttp://demonstrations.wolfram.com/ALineCrossingTwoParallelLinesMakesAlternateAnglesEqual/]]>http://demonstrations.wolfram.com/ALineCrossingTwoParallelLinesMakesAlternateAnglesEqual/Eratosthenes's Measure of the Earth's Circumferencehttp://demonstrations.wolfram.com/EratosthenessMeasureOfTheEarthsCircumference/]]>http://demonstrations.wolfram.com/EratosthenessMeasureOfTheEarthsCircumference/Sum of Exterior Angles of a Polygonhttp://demonstrations.wolfram.com/SumOfExteriorAnglesOfAPolygon/]]>http://demonstrations.wolfram.com/SumOfExteriorAnglesOfAPolygon/Interior and Exterior Angles of Equilateral Figureshttp://demonstrations.wolfram.com/InteriorAndExteriorAnglesOfEquilateralFigures/]]>http://demonstrations.wolfram.com/InteriorAndExteriorAnglesOfEquilateralFigures/Einstein's Most Excellent Proofhttp://demonstrations.wolfram.com/EinsteinsMostExcellentProof/]]>http://demonstrations.wolfram.com/EinsteinsMostExcellentProof/Oriented Triangle Angleshttp://demonstrations.wolfram.com/OrientedTriangleAngles/]]>http://demonstrations.wolfram.com/OrientedTriangleAngles/Parallel Lines: Angles with a Transversalhttp://demonstrations.wolfram.com/ParallelLinesAnglesWithATransversal/]]>http://demonstrations.wolfram.com/ParallelLinesAnglesWithATransversal/