1. Limited time only! Sign up for a free 30min personal 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!

Need help with a problem

  1. Aug 10, 2008 #1
    This is a problem from my homework set.

    I'm so close but I'm tangled up at the end...

    Integrate/ x arccos(x)dx

    So far I am at

    (x^2)/2 arccosx - Int/ (x^2)/ (2 sqrt(x^2 - 1))

    Can figure out how to integrate this part.
  2. jcsd
  3. Aug 10, 2008 #2


    User Avatar
    Science Advisor
    Homework Helper

    I hope you mean sqrt(1-x^2). I would try a substitution like x=sin(u).
  4. Aug 10, 2008 #3
    You are correct. Thankyou!
  5. Aug 10, 2008 #4
    I'm not sure I'm reading this right. Is the part inside the integral,

    x * arccos(x)?

    if so, what about the substitution u = arccos(x), so that x=cos(u), and dx = -sin(u) du? Then it becomes the integral of -u*sin(u)*cos(u) du

    I'd probably try repeated integration by parts to solve the new integral.
  6. Aug 10, 2008 #5
    Never mind, seems it was answered while I was typing :)
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Similar Discussions: Need help with a problem
  1. Problem Need help. (Replies: 1)