Creation of this applet was inspired by a [url=https://twitter.com/gogeometry/status/858760677179236353]tweet[/url] from [url=https://twitter.com/gogeometry]Antonio Gutierrez[/url]. [br][br][b][color=#ff7700]You can move the soon-to-appear ORANGE POINT anywhere you'd like. [/color][/b][br][b]You can also change the position(s) of any of the BIG WHITE POINT(S). [/b][br][br][b][color=#0000ff]How can you formally prove what is dynamically being illustrated here? [/color][/b]