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Homework Help: Trigonometric integrals

  1. Nov 13, 2005 #1
    the two problems are
    the integral of (sec^3x)(tan x)dx
    and the integral of (sec^4x)(tan x)dx

    will substitution work for both of these problems
  2. jcsd
  3. Nov 13, 2005 #2


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    Why don't you just try substitution and see if it works?
  4. Nov 13, 2005 #3
    I did and I got an answer for both, but for some reason I think I should follow the rule and change the sec^4x to (tan+1)(sec^2x)

    and you dont get the same answer when you do it like that

    if you just strait substitute you get sec^7x/5
    and if you change a sec^2x to 1+tan you get tan^4x/2
    I think, thats if im even doing it right
  5. Nov 13, 2005 #4


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    Replace tan(x) by sin(x)/cos(x) (bearing in mind that sec(x) = 1/cos(x)) and the substitution should be clear :smile:
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