(** If x<90 then x+90<180 (two lemmas) *)

(* Specifications: *)
Lemma acute_per__sams : forall A B C D E F, A <> B -> B <> C ->
Per A B C -> Acute D E F -> SAMS A B C D E F.
Lemma acute_per_suma__nbet : forall A B C D E F G H I, A <> B -> B <> C ->
Per A B C -> Acute D E F -> SumA A B C D E F G H I -> ~ Bet G H I.