Creation of this applet was inspired by a [url=http://www.gogeometry.com/school-college/2/p1166-triangle-circle-perpendicular-diameter-congruence-math.htm]post[/url] from Antonio Gutierrez ([url=http://www.gogeometry.com/]GoGeometry[/url]). [br][br]You can move any 1 (or more) of the LARGER POINTS anywhere you'd like.[br]You can control the size of the angle with [b][color=#666666]gray vertex[/color][/b] by using the [color=#666666][b]gray slider. [/b][/color] [br][br][b][color=#9900ff]How can we formally prove what this applet informally illustrates? [/color][/b]