Creation of this resource was inspired by a [url=https://twitter.com/gogeometry/status/1003393090110087169]tweet[/url] from [url=https://twitter.com/gogeometry]Antonio Gutierrez[/url]. [br][br]Below, the [b][color=#38761d]green circle[/color][/b] is internally tangent to the [color=#bf9000][b]manila circle[/b][/color]. [br]You can move the [b]LARGE POINTS[/b] anywhere you'd like [b]AT ANY TIME[/b]. [br][br][b][color=#1e84cc]How can we formally prove what is dynamically illustrated here? [/color][/b]