Require Export GeoCoq.Tarski_dev.Ch05_bet_le.
Ltac eCol := eauto with col.
Section T6_1.
Context `{TnEQD:Tarski_neutral_dimensionless_with_decidable_point_equality}.

Lemma l6_16_1 : forall P Q S X, P<>Q -> Col S P Q -> Col X P Q -> Col X P S.