Section L13_1.
Context `{TnEQD:Tarski_neutral_dimensionless_with_decidable_point_equality}.
(** Pappus Desargues *)

Lemma cong_perp_conga : forall A B C P,  Cong A B C B -> Perp A C B P -> CongA A B P C B P /\ TS B P A C.