Creation of this applet was inspired by a [url=https://twitter.com/gogeometry/status/851127775989817346]tweet[/url] from [url=https://twitter.com/gogeometry]Antonio Gutierrez[/url]. [br][br]You can move any of the large white points anywhere you'd like (at any time.) [br][br][b][color=#0000ff]How can you formally prove what this applet informally illustrates? [/color][/b]