GoGeometry Action 142!

Creation of this applet was inspired by a [url=http://www.gogeometry.com/school-college/p940-circle-tangent-secan-parallel-90-degrees-midpoint.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 [b]ANY TIME. [/b] [br][br]How would you describe the phenomena you see in your own words? [br][br][b][color=#0000ff]How can we formally prove what is dynamically illustrated here? [/color][/b]
Quick (Silent) Demo

Information: GoGeometry Action 142!