Hello, I would like to ask a question which I can't figure out by myself, I'll skip chatter and shoot it:

I need to calculate the length of the perimeter of the circle, but I don't know how I can do that when no lengths at all have been given, so please advise.

This is how I progressed: Aijaa.com - 5598188.jpg

Oh, and I have a 9 hour deadline on this, starting now :X