(** If x+x>180 then x>90. *)

(** If doubling two acute angles makes the same result, then these angles are congruent *)
Lemma sams2_suma2__conga : forall A B C D E F A' B' C',
SAMS A B C A B C -> SumA A B C A B C D E F ->
SAMS A' B' C' A' B' C' -> SumA A' B' C' A' B' C' D E F ->
CongA A B C A' B' C'.