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Try to approach the problem systematically.
As you go along try to understand why the graph takes the shape that it does:
Could the dot have been on the centre of a polygon?
Try for each of the polygons.
Could the dot have been on the centre of the base of a polygon?
Try for each of the polygons.
Could the dot have been on the centre of one of the sloping sides of a polygon?
Try for each of the polygons.
Could the dot have been on the centre of a side opposite the base of a polygon?
Try for each of the polygons.
Could the dot have been on a vertex opposite the base of a polygon?
Try for each of the polygons.
Could the dot have been on a vertex on the base of a polygon?
Try for each of the polygons...
Alternatively...