     # triangle in this triangulation, if any, which contains the two or three
     # given vertices in the correct order.
     find: (a, b, c) ->
-      # If three vertices are given, we look for all three possible vertex
-      # orders with the same orientation in the triangle list.  Otherwise, we
-      # look for the corresponding third vertex, if any, and call find
-      # recursively.
      if c?
         seq(seq(a, b, c), seq(b, c, a), seq(c, a, b)).
           find((t) => @triangles__.contains(t))

    # The method `plus` creates a new Delaunay triangulation with the given
    # `Point2d` instance added as a site.
    plus: (p) ->
      # We return the current instance unchanged if the site is already in.
      if @sites__.contains p
        this
      # Otherwise, there's work to do...
      else
        # ...


# outside or on the circle through points a, b and c. A positive return value
# means inside, zero means on and a negative value means outside.
inclusionInCircumCircle = (a, b, c, d) ->
  liftedNormal(a, b, c).dot lift(d).minus lift(a)


