1. The problem statement, all variables and given/known data Hi, I'm trying to complete my laboratory write up over my christmas break, and I'm struggling to understand how to do part of it. I emailed the lab demonstrator on December 9th, and the head of labs on the 18th and I've had no reply off either, so I'd really appreciate it if you guys could try and help me! I need to calculate the theoretical value of the principle second moment of area for an L shaped section. Using a Mohr's circle apparently. Here is a scan of the lab sheet explaining what I need to do.. I just don't understand how: 2. Relevant equations http://dl.dropbox.com/u/630750/Screen%20Shot%202011-12-23%20at%2010.08.40.png [Broken] 3. The attempt at a solution If someone can try to explain what I'm supposed to do that would be so helpful! Thank you.