1. ## Calc trig help

2. Just split interval $[0 ; \pi]$ in $\left[0 ; \frac{\pi}{2}\right]$ and $\left[\frac{\pi}{2} ; \pi\right]$ where the sign of cos is constant

3. Split the absolute value cosx into...

cosx from (0,pi/2)

-cosx from (pi/2, pi)

into separate integrals

Then have fun integrating.