Creation of this applet was inspired by a [url=https://twitter.com/gogeometry/status/939543923999100928]tweet[/url] from [url=https://twitter.com/gogeometry]Antonio Gutierrez[/url] (GoGeometry). [br][br]You can move the [b]LARGE POINTS[/b] (vertices of the right triangle) anywhere you'd like. [br][br][b][color=#0000ff]How can we formally prove what is dynamically being illustrated here? [/color][/b]