(** Prop 7   **)

Lemma tree_points_onc_cop2 : forall O P Q, O <> P -> exists A B C,
A <> B /\ A <> C /\ B <> C /\ OnCircle A O P /\ OnCircle B O P /\ OnCircle C O P /\
Coplanar A B C O /\ Coplanar A B C Q.