# Thread: Trignometric Integrals

1. ## Trignometric Integrals

Hey, so i did this problem and got -8/15, but then answer at the back was positive 8/15. Can someone help me out?
Thanks in advance! (You have to click on the photo twice to rotate it upright)

2. ## Re: Trignometric Integrals

You changed the bound of the integral wrong hehe. When u=cosx, then your lower bound with respect to u is 1 and upper bound is zero. Always remember that $\int_{1}^{0} =-\int_{0}^{1}$ so you have to use a property of integral to make the lower bound 0 and upper bound 1, but you have to multiple the integral by -1. That will cancel out your negative and you will get 8/15.