Creation of this resource was inspired by a [url=http://gogeometry.com/problem/p622_intersecting_circles_concyclic_points_online_geometry.htm]problem[/url] posted by [url=https://twitter.com/gogeometry]Antonio Gutierrez[/url] (GoGeometry). [br][br]You can move [b]LARGE POINTS a[/b]nywhere you'd like. [br]In addition, the [b][color=#cc0000]slider[/color][/b] alters the radius of the [b][color=#cc0000]circle on the right[/color][/b]. [br]The [b][color=#0000ff]circle on the left[/color][/b] is moveable as well. [br][br][b]How can we formally prove what is dynamically illustrated here? [/b][br]