Section T10.
Context `{TnEQD:Tarski_neutral_dimensionless_with_decidable_point_equality}.
Goal forall A B C D, ~ Coplanar D C B A -> ~ Coplanar A B C D.

(** Here we need the assumption that A<>B *)
Lemma is_image_col_cong : forall A B P P' X, A<>B ->
Reflect P P' A B -> Col A B X -> Cong P X P' X.