Section Pappus_Pascal.
Context `{TE:Tarski_euclidean}.
(*****strange ****)

Lemma cop_per2__perp : forall A B X Y,
A <> B -> X <> Y ->
(B <> X \/ B <> Y) ->
Coplanar A B X Y ->
Per A B X -> Per A B Y ->
Perp A B X Y.