Creation of this applet was inspired by a [url=https://twitter.com/gogeometry/status/884512500531834880]tweet[/url] from [url=https://twitter.com/gogeometry]Antonio Gutierrez[/url]. [br][br][b][color=#ff00ff]You can control the size of the pink angle (soon to appear) by using the pink slider. [/color][/b][br][b]You can also move any of the BIG WHITE POINTS anywhere you'd like.[/b] [br][br][color=#ff00ff][b]How can we formally prove what this applet informally illustrates? [/b][/color]