1. The problem statement, all variables and given/known data Find the intervals of increase and decrease of secx on the interval (-pi/2, 3pi/2). 2. Relevant equations 3. The attempt at a solution I found the derivative and set it equal to zero to get the critical points: f'(x)=sinx/cos^2x 0=sinx/cos^2x 0=sinx x= 0 and pi (restricted by interval) Now to find the intervals of increase and decrease I am lost? It says think about the unit circle?