# Animation 81

What theorem's proof is being dynamically illustrated here?
And how does this applet actually informally show this theorem to be true?
(Feel free to move the white points *A*, *B*, *C* anywhere you'd like.)

What theorem's proof is being dynamically illustrated here?
And how does this applet actually informally show this theorem to be true?
(Feel free to move the white points *A*, *B*, *C* anywhere you'd like.)