Remember rotational symmetry means if you turn it you end up with the same figure you started with. This happens with regular polygons since each angle is congruent. To find the angle of rotation you divide 360 by the number of angles. So if you rotated 360 degrees, that means 360/360=1. Your figure only had one angle, so it can't even be a polynomial! Also, every figure in the world will look exactly like it started if rotated 360 degrees, so this would not be logical.