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!

Difficult integration

  1. Feb 6, 2008 #1
    integrate sin^4(2x) without using the reduction formula.im stuck.
    im pretty sure you have to use integration by parts.
     
  2. jcsd
  3. Feb 6, 2008 #2
    Try using double-angle formulae a couple of times.
     
  4. Feb 6, 2008 #3

    rock.freak667

    User Avatar
    Homework Helper

    The double angle formula for cos will help I believe.
     
  5. Feb 7, 2008 #4
    don't know what the reduction formula is, maybe it is the trick i'm about to give you

    [tex] \int sin(2x)^4 dx = \frac{1}{2} \int sin(u)^4 du = \frac{1}{2} \int (sin(u)^2)^{3/2} sin(u) du = \frac{1}{2} \int (1-cos(u)^2)^{3/2} sin(u)du = \frac{1}{2} \int (1-t^2)^{3/2} dt = \int sqrt((1-t^2)^3) [/tex]

    maybe you can do this???, of cause you have to keep track of all the substitutions to get how sin and y are related but that should be possible.
     
    Last edited: Feb 7, 2008
  6. Feb 7, 2008 #5
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Difficult integration
  1. Difficult integral (Replies: 7)

  2. Difficult integral (Replies: 19)

  3. Difficult integral (Replies: 3)

  4. Difficult integral (Replies: 26)

  5. Difficult integrals? (Replies: 3)

Loading...