(** This lemma used to be an axiom in previous versions of Tarski's axiom system. It is a been shown to a theorem by Gupta in his Phd 1965. *)
(** This corresponds to l9_6 in Tarski's book. *)

Lemma cong3_cop2__col : forall A B C P Q,
Coplanar A B C P -> Coplanar A B C Q ->
P <> Q -> Cong A P A Q -> Cong B P B Q -> Cong C P C Q ->
Col A B C.