Question

Please reference this: http://www.personal.psu.edu/pxt156/Subjects/Calculus/Leibniz/leibnizIntegration.pdf

I am confused as to what exactly happens between step 5 and 6. Is it some sort of algebra technique I am missing? Is this an example of trig substitution? Everything else is fine, I just don't understand how the integral was evaluated to give the result in step 6. Any pointers would be helpful!