1. The problem statement, all variables and given/known data Question is attached in this post. 2. Relevant equations Question is attached in this post. 3. The attempt at a solution I set the integral as ∫(cos^1/2(x))(1-cos^2(x))(sinx) dx from 0 to π/2 Next I used u-substitution where I let u=cosx and du=-sinxdx I solved out the integral and ended up getting 7/6 as my answer, however the correct answer is 8/21. Was my approach incorrect?