dont we consider the perpendicular length from the centre of mass, so that will be c/2.
now even if we take the distance from centre to left corner, it will be c2/4 + c2/16 = 5c2/16.
so torque will be mg x \sqrt{5}c/4
and equating it to Ia = (5mc2/8 + 5mc2/4)a
gives a =...