GoGeometry Action 79!

Creation of this applet was inspired by a [url=https://twitter.com/gogeometry/status/886715206977691648]tweet[/url] from [url=https://twitter.com/gogeometry]Antonio Gutierrez[/url].[br][br]Feel free to move the [b]LARGE POINTS[/b] anywhere you'd like.[br]How can we formally prove the phenomena dynamically illustrated here?
Quick (silent) demo

Information: GoGeometry Action 79!