Creation of this applet was inspired by a [url=http://www.gogeometry.com/school-college/p865-parallelogram-similarity-midpoint-parallel.htm]post[/url] from [url=https://twitter.com/gogeometry]Antonio Gutierrez[/url] (GoGeometry). [br][br][b][color=#38761d]You can change the measure of the green angle (soon to form) using the green slider.[/color][/b][br]Feel free to move the [b][color=#ff7700]BIG ORANGE POINT (soon to appear)[/color][/b] at any time as well. [br]The [b]LARGE WHITE POINTS [/b]are also moveable. [br][br][br][b][color=#ff00ff]How can we formally prove what is informally illustrated here? [/color][/b]