Section Saccheri.
Context `{TnEQD:Tarski_neutral_dimensionless_with_decidable_point_equality}.
(** The two following lemmas come from Theorem 21.10 *)
(** The five following lemmas come from Theorem 21.8 *)
(** The two following lemmas constitute Theorem 21.11 *)
(** The four following constitute Theorem 22.3 *)
(** The six following lemmas constitute Theorem 22.5 *)
(** The three following lemmas constitute Omar Khayyam's Theorem (22.6) *)
(** The two following lemmas come from Theorem 22.4 *)
(** This comes from Martin's proof in Theorem 22.10 *)
(** Saccheri's three hypotheses *)
Definition hypothesis_of_right_saccheri_quadrilaterals := forall A B C D, Saccheri A B C D -> Per A B C.
Definition hypothesis_of_acute_saccheri_quadrilaterals := forall A B C D, Saccheri A B C D -> Acute A B C.
Definition hypothesis_of_obtuse_saccheri_quadrilaterals := forall A B C D, Saccheri A B C D -> Obtuse A B C.

Lemma t22_14_aux : forall A B C,
~ Col A B C -> Acute A B C -> Acute A C B ->
exists A', Bet B A' C /\ Per B A' A /\ Per C A' A /\
CongA B A' A C A' A /\ CongA A B C A B A' /\ CongA B C A A' C A /\ TS A A' B C.