GoGeometry Action 2!

Creation of this applet was inspired by a [url=https://twitter.com/gogeometry/status/833754643083776000]tweet[/url] posted by [url=https://twitter.com/gogeometry]Antonio Gutierrez[/url]. [br][br][b][color=#0000ff]How can you formally prove what this applet informally illustrates? [/color][/b]
Quick (Silent) Demo

Informacja: GoGeometry Action 2!