1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Having trouble finding the Integral

  1. Oct 6, 2006 #1

    I am having trouble getting started with this integral.

    [itex]\int sin2x ln(cos2x) dx[/itex]

    My first thought goes to using integration by parts to solve this but I am still getting stuck. I also know that [itex]sin2x = 2sinxcosx[/itex] but again I'm not seeing how that would help me so I'm back to integration by parts.

    My issue is if I set [itex]u = ln(cos2x)[/itex] then I'm having trouble figuring out what [itex]du[/itex] is. I know it's just finding the derivative but I can't for the life of me remember how to do that. Then if I set [itex]dv = sin2x dx[/itex] then [itex]v = - \frac{1}{2} cos2x[/itex]

    Any help or suggestions would be greatly appreciated.
  2. jcsd
  3. Oct 6, 2006 #2


    User Avatar
    Science Advisor
    Homework Helper
    Gold Member
    Dearly Missed

    Set u=cos(2x).
  4. Oct 6, 2006 #3
    Oh my gosh...I was making that WAY harder then it needed to be. Thank you very much arildno.
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?