Checking my calculus solution against the textbook

[p3t3r1]

I solved this question a bit differently from the textbook's solution manual and got a very different answer. I am wondering if this solution is sound? Thanks.

 

[nicksauce]

Well you can always check yourself by differentiating your answer. However, on the last line (cot^2 x * sinx) is not equal to cotx * csc x.

 

[rocomath]

I like the first line. I'ma try that next time and get wowz.