proposition: Lemma l11_44_1 : forall A B C, ~ Col A B C -> (CongA B A C B C A <-> Cong B A B C).
proof: Proof. intros; assert_diffs; split; intro; auto using l11_44_1_b, l11_44_1_a. Qed.
imports: GeoCoq.Tarski_dev.Ch10_line_reflexivity_2