Section Suma_2.
Context `{TnEQD:Tarski_neutral_dimensionless_with_decidable_point_equality}.
(** ABC <= ABC + DEF. *)
(** DEF <= ABC + DEF. *)
(** LeA preserves SAMS. *)
(** SumA preserves LeA. *)
(** Unicity of the difference of angles. *)
(** Unicity of the difference on the left. *)

Lemma sams2_suma2__conga123 : forall A B C A' B' C' D E F G H I,
SAMS A B C D E F -> SAMS A' B' C' D E F ->
SumA A B C D E F G H I -> SumA A' B' C' D E F G H I ->
CongA A B C A' B' C'.