Lemma ThreeEmbeddedTriangles : forall A B C D E F G : Point, Clockwise A B C -> HalfLine A B D -> HalfLine A C E -> Angle A B C = Angle A D E -> Angle A C B = Angle A E D -> Between A D F -> Between A E G -> Distance D F = Distance A B -> Distance E G = Distance A C -> Angle A B C = Angle A F G /\ Angle A C B = Angle A G F.