1. The problem statement, all variables and given/known data http://i.imgur.com/7ZRsVj5.png 2. Relevant equations I can't apply correct method ! 3. The attempt at a solution In bigger figure, i cut into 8 equal parts.So , total moment of inertia=8 I But it's wrong ! I know it's wrong because i can't able to find angle between any two sides when i cut into 8 equal parts. So,just as a guessing approach , i supposed each part is equal to I . Therefore,corresponding to total 8 I.