My conclusion was actually that the points M and N must be the same point, which then implies that they also coincide with R. The drawing can be "faked" by ske

My conclusion was actually that the points M and N must be the same point, which then implies that they also coincide with R. The drawing can be "faked" by sketching the diameters to be a bit off-center, which results in M,N and R not being exactly the same point. No ?