Elegant Geometry Proof

This is a very cool and elegant visual proof. Given: Triangle ABC with equilateral triangles drawn on each side. Prove: The segments connecting each vertex of Triangle ABC to the vertex that's not A, B, or C of the equilateral triangle on its opposite side are all congruent. Drag around points A, B and/or C, to see that the segments always seem to be congruent. To see the proof, slide the rotation slider from 0 to 60.