Call this point C. Already, we know AC = BC = MC.But C must also lie on the perp. bis. that gave NThere are infinitely many circles that can be centred on this line that go through A and B, including one that also goes through N.It remains to show that the circle that goes through A, B and N is also the circle that goes through A. B and M.They are, but the proof eludes me at present.Back later to