Creation of this applet was inspired by a [url=https://twitter.com/gogeometry/status/891080930667921409]tweet[/url] from[url=https://twitter.com/gogeometry] Antonio Gutierrez[/url] (GoGeometry). [br][br][b]Feel free to move any of the BIG POINTS anywhere you'd like at any time. [br][/b][br][b][color=#9900ff]How can we formally prove what this applet informally illustrates?[/color][/b]