(** This development is inspired by The Foundations of Geometry and the Non-Euclidean Plane, by George E Martin, chapter 22 *)
Section Archimedes.
Context `{TnEQD:Tarski_neutral_dimensionless_with_decidable_point_equality}.

Lemma t22_19 :
archimedes_axiom ->
forall A B C D, Saccheri A B C D -> ~ Obtuse A B C.