Creation of this applet was inspired by a [url=https://twitter.com/gogeometry/status/987479277418491906]tweet[/url] posted by [url=https://twitter.com/gogeometry]Antonio Gutierrez[/url] (GoGeometry). [br][br]You can move the [b]LARGE WHITE VERTICES[/b] of the triangle anywhere you'd like [b]AT ANY TIME. [/b] [br]You can also alter the size of the [b][color=#1e84cc]BLUE INTERIOR ANGLE[/color][/b] by using the [color=#1e84cc][b]BLUE SLIDER. [/b][/color][br][br][b]How can we formally prove the 3 (soon-to-appear) lines are[color=#ff00ff] ALWAYS CONCURRENT? [/color][/b]