∫tan x

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  1. sabre2th1's Avatar
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    • Location: Southampton
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    ∫tan x
    ∫tan x =

    ∫(sin x/cos x)

    Sin x/cos x is of the form f'(x)/f(x)

    therefore the ∫sin x/cos x = -ln|cos x| + c

    However, my book also states that the ∫tan x = ln|sec x| +c ?
  2. cpdavis's Avatar
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    Re: ∫tan x
    (Original post by sabre2th1)
    ∫tan x =

    ∫(sin x/cos x)

    Sin x/cos x is of the form f'(x)/f(x)

    therefore the ∫sin x/cos x = -ln|cos x| + c

    However, my book also states that the ∫tan x = ln|sec x| +c ?
    How can you rewrite this?
  3. Blutooth's Avatar
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    • Location: London
    • Posts: 1,943
    Re: ∫tan x
    (Original post by sabre2th1)
    ∫tan x =

    ∫(sin x/cos x)

    Sin x/cos x is of the form f'(x)/f(x)

    therefore the ∫sin x/cos x = -ln|cos x| + c

    However, my book also states that the ∫tan x = ln|sec x| +c ?
    Remember that,
    -ln(a)=ln(1/a)
  4. sabre2th1's Avatar
    • Exalted and Worshipped Member
    • Location: Southampton
    • Posts: 1,046
    Re: ∫tan x
    (Original post by cpdavis)
    How can you rewrite this?

    (Original post by Blutooth)
    Remember that,
    -ln(a)=ln(1/a)
    Just as you wrote this, I remembered ! Thanks
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