End METRIC.
Section ANGLES.
Parameter AS : Set.
Parameter Angle : Point -> Point -> Point  -> AS.

(* Specifications: *)
Axiom CongruentItself : forall A B C D E : Point,
A <> B ->
A <> C ->
HalfLine A B D ->
HalfLine A C E ->
Angle B A C = Angle E A D.
Axiom CongruentSAS : forall A B C D E F : Point,
A <> B ->
A <> C ->
Distance A B = Distance D E ->
Distance A C = Distance D F ->
Angle B A C = Angle E D F ->
Distance B C  = Distance E F.
Axiom CongruentSSS : forall A B C D E F : Point,
A <> B ->
A <> C ->
Distance A B = Distance D E ->
Distance A C = Distance D F ->
Distance B C = Distance E F ->
Angle B A C = Angle E D F.
Axiom SumAngles : forall A B C D E : Point,
Clockwise A B C ->
Clockwise A C D ->
Clockwise A D E ->
Angle B A C = Angle A C D ->
Angle D A E = Angle A D C ->
Between B A E.