Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Can someone point me in the right directon

  1. Aug 2, 2007 #1
    the problem is to intigrate cot[tex]^{2}[/tex]x

    now i kow that cot[tex]^{2}[/tex]x = [tex]\frac{cos^{2}x}{sin^{2}x}[/tex]

    now iv tryed various substitutions like usig the power reducton forumulas...
    and then using double angle substiutions but nothin seems to work for me

    so i was wondering if somone could just tell me where to start so i can
    finish this question.... been trying to figure this out for like a hour now

    thanks in advance
     
    Last edited: Aug 2, 2007
  2. jcsd
  3. Aug 2, 2007 #2

    HallsofIvy

    User Avatar
    Science Advisor

    Use the identities 1+ cot2(x)= csc2(x) so that cot2(x)= csc2(x)- 1. Since you know that the derivative of cot(x) is csc2(x), that should be easy.
     
  4. Aug 2, 2007 #3
    Wow that was suprisingly simple thank alot yea i didnt know about that identity that was the first time iv used it. Thnx alot great help
     
  5. Aug 2, 2007 #4

    Kurdt

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    There are many pages that list trig identities. Whenever I work with trig functions I always just open a page and have a look at how the functions in the question are related. There are loads of pages, but I do like wikipedias as it has a list of the 6 trig functions in terms of the others which is very handy for some integration questions when trig substitution is needed.

    http://en.wikipedia.org/wiki/Trigonometric_identity
     
  6. Aug 2, 2007 #5
    Wow very nice im gonna bookmark this page right away thnx again!
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook