Creation of this applet was inspired by a [url=https://twitter.com/gogeometry/status/843495492793319424]tweet[/url] from [url=https://twitter.com/gogeometry]Antonio Gutierrez[/url]. [br][br][b][color=#0000ff]How can you formally prove what this applet informally illustrates? [br][br][/color]Feel free to move the BIG WHITE POINTS anywhere you'd like! [/b][br][b][color=#9900ff](The purple points control the center and radius of the circle.) [/color][/b]