Creation of this applet was inspired by a [url=https://twitter.com/gogeometry/status/915592648274128898]tweet[/url] from [url=https://twitter.com/gogeometry]Antonio Gutierrez[/url]. [br][br]You can move the [b]LARGE WHITE VERTICES[/b] of the triangle anywhere you'd like AT ANY TIME.[br][b][color=#1e84cc]You can also move the 2 LARGE BLUE POINTS anywhere you'd like at any time.[/color][/b][br][b][color=#ff00ff]You can adjust the size of the pink angle by using the pink slider. [/color][/b][br][br][b]How can we formally prove the phenomenon dynamically illustrated here? [/b]