Library GeoCoq.Utils.triples

We circumvent a limitation of type class definition by defining a polymorphic type for a triple of elements which will be used to define an angle by instantiating A with Point

Record Triple {A:Type} : Type := build_triple {V1 : A ; V : A ; V2 : A ; Pred : V1 V V2 V}.

Record Couple {A:Type} : Type := build_couple {P1: A ; P2 : A ; Cond: P1 P2}.