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INtegration by substitution followed by parts:

  1. Feb 17, 2007 #1
    ... of (x tan^2 x). i dunno how to do it. pls help
     
  2. jcsd
  3. Feb 17, 2007 #2

    cristo

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    Well, what have you tried? This is clearly homework! Try writing tanx in terms of sinx and cosx.
     
  4. Feb 17, 2007 #3
    i tried that. i even tried using trig identities for the expansion of tan^2 but i got no where. im lost...
     
  5. Feb 17, 2007 #4
    any ideas?
     
  6. Feb 17, 2007 #5
    this is by-parts integration because you have two functions multiplied by each other.
    But before you do that you should use a trig identity (think of an identity which will give you an easily integratable trig function).
     
  7. Feb 18, 2007 #6

    cristo

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  8. Feb 18, 2007 #7

    Gib Z

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    Good work though :P
     
  9. Feb 18, 2007 #8

    cristo

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    Hint: Do you know an identity for tan2x in terms of, say, sec2x?

    Try using this then integrate by parts. Post your work so we can help you.
     
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