Drawing points on Argand plane 
The points $5 + 5i$, $1− 3i$, $− 4 + 2i$ and $−2 + 6i$ in the
  Argand plane are:
(a) Collinear
(b) Concyclic
(c) The vertices of a parallelogram
(d) The vertices of a square

So when I drew the diagram, I got an rectangle in the 1st and 2nd quadrant. So, are they vertices of parallelogram? I am not sure! 

Its not collinear, nor a square, nor a parallelogram. Therefore, it must be Concyclic
