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Please help me with the integral (1 / (cosxcotx))?

I just cant figure out what way to go about it?

INT (1 / (cosxcotx))

I'm figuring it should come out to something like (secx) but cant find the means thereto. Thanks!

3 Answers

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  • 1 decade ago
    Favorite Answer

    this is an identity you'll get to memorize!! but here's one way to figure it out

    1/cosx = secx and 1/cotx =tanx

    so the integral sec(x)tan(x) dx can be found using u substitution

    u=sec(x)

    du i.e the derivative of sec(x) = tan(x)sec(x) dx

    integral 1 du = u + constant

    u = sec(x)

    so the answer is

    sec(x) + constant!!

    kind of a silly answer huh! gotta love trig identities!

  • ?
    Lv 7
    1 decade ago

    cotx= cosx /sinx

    1/ (cosx cotx)= sin x/cos^2x

    INT (1/ (cosx cotx) dx = INT (sinx/cos^2x) dx

    u=cosx , du =-sin x dx

    = - INT (1/u^2) du = (1/u ) = 1/cosx = sec x + C

  • 1 decade ago

    cot x = cos x / sin x

    cos x cot x = cos² x / sin x

    INT ( 1/(cos x cot x))dx = INT (sin x / cos² x) dx

    sin x dx = d (- cos x)

    INT ( 1/(cos x cot x))dx = INT d(- cos x) / cos² x = - INT dy / y² = 1/y + C = 1/cos x + C = sec x + C

    (temporary y = cos x)

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