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

(* Specifications: *)
Lemma obtuse__nsams : forall A B C, Obtuse A B C -> ~ SAMS A B C A B C.
(** If x+x<180 then x<90. *)
Lemma nbet_sams_suma__acute : forall A B C D E F, ~ Bet D E F -> SAMS A B C A B C ->
SumA A B C A B C D E F -> Acute A B C.