fact: Definition alternative_playfair_s_postulate := forall A1 A2 B1 B2 C1 C2 P, Perp2 A1 A2 B1 B2 P -> ~ Col A1 A2 P -> Col P B1 B2 -> Coplanar A1 A2 B1 B2 -> Par A1 A2 C1 C2 -> Col P C1 C2 -> Col C1 B1 B2 /\ Col C2 B1 B2.
imports: GeoCoq.Tarski_dev.Definitions