Section Bisector.
Context `{TnEQD:Tarski_neutral_dimensionless_with_decidable_point_equality}.
(** Existence of the interior bisector of an angle. *)

Lemma not_col_efoot_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-> Cong I H1 I H2->
Perp A B I H1 -> Perp B C I H2 -> H1 <> B /\ H2 <> B.