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how to solve for the integral of 1 over the cos(x) + 1?

Hey again, so to write it, out it is:

S(1/cos(x) + 1) dx The 'S' is my integral sign.

Anyone?

4 Answers

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  • 1 decade ago
    Favorite Answer

    Use the identity (cosx+1)/2=cos^2(x/2).

    Then S=Sdx/[2cos^2(x/2)]=S(1/cos^2(x/2)) d(x/2)=tan(x/2)

    The simplest you can get!!!

  • Como
    Lv 7
    1 decade ago

    ∫(1/cos x )+ 1dx = ∫ sec x dx + x + C

    = log(sec x + tan x) + x + C

    Note that the integral of sec x is a standard integral, log(sec x + tan x)

  • 1 decade ago

    I would multiply 1/(cosx + 1) by (cosx -1)/(cosx - 1).

    Then you will have

    (cosx - 1)/(cos²x - 1),

    (cosx - 1)/(-sin²x),

    (-cosx)/(sin²x) + (1)/(sin²x),

    -cotxcscx + csc²x.

    The derivative of cscx is -cotxcscx and the derivative of cotx is csc²x.

    Feel free to email me for further clarifications.

  • 1 decade ago

    I assume you mean 1/(cos(x) + 1).

    First let's rearrange the terms to make it easier to integrate.

    1/(cos(x) + 1) = 1/[1 + cos(x)]

    = [1 - cos(x)]/{[1 + cos(x)][1 - cos(x)]}

    = [1 - cos(x)]/[1 - cos²(x)] = [1 - cos(x)]/sin²(x)

    = 1/sin²(x) - cos(x)/sin²(x) = csc²(x) - (cot(x))(csc(x))

    Now we can integrate.

    ∫1/(cos(x) + 1)dx = ∫{csc²(x) - (cot(x))(csc(x))}dx

    = -cot(x) + csc(x) + C

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