Definition Supplementary (alpha beta : AS) :=
exists A  : Point,  exists B  : Point,  exists C : Point,  exists D : Point, 
	A <> C /\ Between B A D /\ Angle B A C = alpha /\ Angle C A D = beta.

Lemma SupplementaryEq : forall alpha beta gamma : AS, Supplementary alpha beta -> Supplementary alpha gamma -> beta = gamma.