1. The problem statement, all variables and given/known data Please see attached image. From the given information, I am having trouble deriving the left and right hand limits, I just can't figure out what these are... 2. Relevant equations None needed. 3. The attempt at a solution In the solution, t is chosen as pi, which I understand. But I just can't figure out how these left and right hand limits are found. Are these limits somehow derived from limits of integration? Here is the solution. Any help will be appreciated.