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    Please can someone help me with this question?

    I know it should be simple but I can't get the answer
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    (Original post by Pixelfairy #1)
    Please can someone help me with this question?
    xtanx - integral of tanx

    xtanx -ln sec x

    xtan x - ln (1/cos)

    pie / 4 - 1/2 ln 2
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    (Original post by tammypotato)
    xtanx - integral of tanx

    xtanx -ln sec x

    xtan x - ln (1/cos)

    pie / 4 - 1/2 ln 2
    Thanks... lol i shouldnt of bothered posting it :rolleyes:
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    (Original post by Pixelfairy #1)
    Thanks... lol i shouldnt of bothered posting it :rolleyes:
    yeah lol
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    (Original post by tammypotato)
    yeah lol
    In all fairness I did post it before you told me how to do it
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    (Original post by Pixelfairy #1)
    In all fairness I did post it before you told me how to do it
    how does INT of xtanx become lnsecx?? do i just have to know that, or is there a way of showing it?
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    (Original post by wonkey)
    how does INT of xtanx become lnsecx?? do i just have to know that, or is there a way of showing it?
    The integral of tan x = ln |sec x|

    INT tan x dx = INT sin x dx/cos x

    u = cos x, du = -sin x dx

    INT -du/u = -ln u + C

    => -ln |cos x| + C

    Using log law nln a = ln a^n:

    ln |(cos x)^-1| + C = ln |sec x| + C
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    (Original post by Nylex)
    The integral of tan x = ln |sec x|

    INT tan x dx = INT sin x dx/cos x

    u = cos x, du = -sin x dx

    INT -du/u = -ln u + C

    => -ln |cos x| + C

    Using log law nln a = ln a^n:

    ln |(cos x)^-1| + C = ln |sec x| + C
    thx so much....i just had in my head that INT of tanx = -lncos x
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    (Original post by Nylex)
    The integral of tan x = ln |sec x|

    INT tan x dx = INT sin x dx/cos x

    u = cos x, du = -sin x dx

    INT -du/u = -ln u + C

    => -ln |cos x| + C

    Using log law nln a = ln a^n:

    ln |(cos x)^-1| + C = ln |sec x| + C
    was i right tho?
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    (Original post by tammypotato)
    was i right tho?

    yes
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    same answer but typed up
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  1. File Type: pdf trig p3.pdf (9.2 KB, 279 views)
 
 
 
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