Math - Calculate a normal vector from three position vectors

This Vector3 constructor calculates a surface normal from three 3D vectors.

public Vector3(Vector3 a, Vector3 b, Vector3 c) {
  var u = b - a; //Requires an overloaded minus
  var v = c - a; //operator for two vector3's.
  X = (u.Y * v.Z) - (u.Z * v.Y);
  Y = (u.Z * v.X) - (u.X * v.Z);
  Z = (u.X * v.Y) - (u.Y * v.X);
  Normalize();
}