private static EdgeAggregator ConstructExteriorRelationship(Triangle tri, Angle extAngle)
{
//
// Acquire the remote angles
//
Angle remote1 = null;
Angle remote2 = null;
tri.AcquireRemoteAngles(extAngle.GetVertex(), out remote1, out remote2);
//
// Construct the new equation
//
Addition sum = new Addition(remote1, remote2);
GeometricAngleEquation eq = new GeometricAngleEquation(extAngle, sum);
//
// For the hypergraph
//
List <GroundedClause> antecedent = Utilities.MakeList <GroundedClause>(tri);
antecedent.Add(extAngle);
return(new EdgeAggregator(antecedent, eq, annotation));
}