Require Export GeoCoq.Tarski_dev.Ch13_1.
Require Export GeoCoq.Highschool.triangles.
Section Bisector.
Context `{TE:Tarski_euclidean}.
(** Existence of the interior bisector of an angle. *)

Lemma not_col_bfoot_not_equality : forall A B C I H1 H2, ~ Col A B C -> Coplanar A B C I ->
Col A B H1 -> Col B C H2 -> CongA A B I I B C->
Perp A B I H1 -> Perp B C I H2 -> H1 <> B /\ H2 <> B.