Creation of this resource was inspired by [url=https://twitter.com/Cshearer41/status/1209063976249810944?s=20]this problem[/url] posted by [url=https://twitter.com/Cshearer41]Catriona Shearer[/url]. [br][br]The two semicircles you see always remain tangent to each other.[br]You can move the [b]LARGE POINTS[/b] in the upper left and lower right corner at any time. [br][br]How can we formally prove the phenomenon dynamically illustrated here?