Creation of this applet was inspired by a [url=http://www.gogeometry.com/school-college/3/p1272-isosceles-triangle-altitude-midpoint-angle.htm]problem[/url] posted by [url=https://twitter.com/gogeometry]Antonio Gutierrez[/url] (GoGeometry). [br][br]You can move any of the [b]LARGE POINTS[/b] anywhere you'd like at any time. [br][br][b][color=#e06666]How can we formally prove the phenomenon dynamically illustrated here? [/color][/b]