Require Export C6_Parallele_Prop.
Section SECANT_LINES_PROPERTIES.

Lemma UniqueIntersectionLines : forall A B C D I J : Point,
A <> B ->
C <> D ->
~EquiDirected A B C D ->
Collinear A B I ->
Collinear A B J ->
Collinear C D I ->
Collinear C D J ->
I = J.