(** If doubling two angles makes the same result, then they are either congruent or supplementary *)

Lemma suma2__or_conga_suppa : forall A B C A' B' C' D E F ,
SumA A B C A B C D E F -> SumA A' B' C' A' B' C' D E F ->
CongA A B C A' B' C' \/ SuppA A B C A' B' C'.