(* Gabriel Braun April 2013 *)
Require Export GeoCoq.Tarski_dev.Ch13_2_length.
Section Angles_1.
Context `{TnEQD:Tarski_neutral_dimensionless_with_decidable_point_equality}.
(************************************* angle *****************************)

Lemma ang_exists : forall A B C, A <> B -> C <> B -> exists a, Q_CongA a /\ a A B C.