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tg^3(x)

Integral of tg^3(x) dx

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01tan3(x)dx\int\limits_{0}^{1} \tan^{3}{\left(x \right)}\, dx
Integral(tan(x)^3, (x, 0, 1))
Detail solution
  1. Rewrite the integrand:

    tan3(x)=(sec2(x)1)tan(x)\tan^{3}{\left(x \right)} = \left(\sec^{2}{\left(x \right)} - 1\right) \tan{\left(x \right)}

  2. There are multiple ways to do this integral.

    Method #1

    1. Let u=sec2(x)u = \sec^{2}{\left(x \right)}.

      Then let du=2tan(x)sec2(x)dxdu = 2 \tan{\left(x \right)} \sec^{2}{\left(x \right)} dx and substitute du2\frac{du}{2}:

      u12udu\int \frac{u - 1}{2 u}\, du

      1. The integral of a constant times a function is the constant times the integral of the function:

        u1udu=u1udu2\int \frac{u - 1}{u}\, du = \frac{\int \frac{u - 1}{u}\, du}{2}

        1. Rewrite the integrand:

          u1u=11u\frac{u - 1}{u} = 1 - \frac{1}{u}

        2. Integrate term-by-term:

          1. The integral of a constant is the constant times the variable of integration:

            1du=u\int 1\, du = u

          1. The integral of a constant times a function is the constant times the integral of the function:

            (1u)du=1udu\int \left(- \frac{1}{u}\right)\, du = - \int \frac{1}{u}\, du

            1. The integral of 1u\frac{1}{u} is log(u)\log{\left(u \right)}.

            So, the result is: log(u)- \log{\left(u \right)}

          The result is: ulog(u)u - \log{\left(u \right)}

        So, the result is: u2log(u)2\frac{u}{2} - \frac{\log{\left(u \right)}}{2}

      Now substitute uu back in:

      log(sec2(x))2+sec2(x)2- \frac{\log{\left(\sec^{2}{\left(x \right)} \right)}}{2} + \frac{\sec^{2}{\left(x \right)}}{2}

    Method #2

    1. Rewrite the integrand:

      (sec2(x)1)tan(x)=tan(x)sec2(x)tan(x)\left(\sec^{2}{\left(x \right)} - 1\right) \tan{\left(x \right)} = \tan{\left(x \right)} \sec^{2}{\left(x \right)} - \tan{\left(x \right)}

    2. Integrate term-by-term:

      1. Let u=sec(x)u = \sec{\left(x \right)}.

        Then let du=tan(x)sec(x)dxdu = \tan{\left(x \right)} \sec{\left(x \right)} dx and substitute dudu:

        udu\int u\, du

        1. The integral of unu^{n} is un+1n+1\frac{u^{n + 1}}{n + 1} when n1n \neq -1:

          udu=u22\int u\, du = \frac{u^{2}}{2}

        Now substitute uu back in:

        sec2(x)2\frac{\sec^{2}{\left(x \right)}}{2}

      1. The integral of a constant times a function is the constant times the integral of the function:

        (tan(x))dx=tan(x)dx\int \left(- \tan{\left(x \right)}\right)\, dx = - \int \tan{\left(x \right)}\, dx

        1. Rewrite the integrand:

          tan(x)=sin(x)cos(x)\tan{\left(x \right)} = \frac{\sin{\left(x \right)}}{\cos{\left(x \right)}}

        2. Let u=cos(x)u = \cos{\left(x \right)}.

          Then let du=sin(x)dxdu = - \sin{\left(x \right)} dx and substitute du- du:

          (1u)du\int \left(- \frac{1}{u}\right)\, du

          1. The integral of a constant times a function is the constant times the integral of the function:

            1udu=1udu\int \frac{1}{u}\, du = - \int \frac{1}{u}\, du

            1. The integral of 1u\frac{1}{u} is log(u)\log{\left(u \right)}.

            So, the result is: log(u)- \log{\left(u \right)}

          Now substitute uu back in:

          log(cos(x))- \log{\left(\cos{\left(x \right)} \right)}

        So, the result is: log(cos(x))\log{\left(\cos{\left(x \right)} \right)}

      The result is: log(cos(x))+sec2(x)2\log{\left(\cos{\left(x \right)} \right)} + \frac{\sec^{2}{\left(x \right)}}{2}

    Method #3

    1. Rewrite the integrand:

      (sec2(x)1)tan(x)=tan(x)sec2(x)tan(x)\left(\sec^{2}{\left(x \right)} - 1\right) \tan{\left(x \right)} = \tan{\left(x \right)} \sec^{2}{\left(x \right)} - \tan{\left(x \right)}

    2. Integrate term-by-term:

      1. Let u=sec(x)u = \sec{\left(x \right)}.

        Then let du=tan(x)sec(x)dxdu = \tan{\left(x \right)} \sec{\left(x \right)} dx and substitute dudu:

        udu\int u\, du

        1. The integral of unu^{n} is un+1n+1\frac{u^{n + 1}}{n + 1} when n1n \neq -1:

          udu=u22\int u\, du = \frac{u^{2}}{2}

        Now substitute uu back in:

        sec2(x)2\frac{\sec^{2}{\left(x \right)}}{2}

      1. The integral of a constant times a function is the constant times the integral of the function:

        (tan(x))dx=tan(x)dx\int \left(- \tan{\left(x \right)}\right)\, dx = - \int \tan{\left(x \right)}\, dx

        1. Rewrite the integrand:

          tan(x)=sin(x)cos(x)\tan{\left(x \right)} = \frac{\sin{\left(x \right)}}{\cos{\left(x \right)}}

        2. Let u=cos(x)u = \cos{\left(x \right)}.

          Then let du=sin(x)dxdu = - \sin{\left(x \right)} dx and substitute du- du:

          (1u)du\int \left(- \frac{1}{u}\right)\, du

          1. The integral of a constant times a function is the constant times the integral of the function:

            1udu=1udu\int \frac{1}{u}\, du = - \int \frac{1}{u}\, du

            1. The integral of 1u\frac{1}{u} is log(u)\log{\left(u \right)}.

            So, the result is: log(u)- \log{\left(u \right)}

          Now substitute uu back in:

          log(cos(x))- \log{\left(\cos{\left(x \right)} \right)}

        So, the result is: log(cos(x))\log{\left(\cos{\left(x \right)} \right)}

      The result is: log(cos(x))+sec2(x)2\log{\left(\cos{\left(x \right)} \right)} + \frac{\sec^{2}{\left(x \right)}}{2}

  3. Add the constant of integration:

    log(sec2(x))2+sec2(x)2+constant- \frac{\log{\left(\sec^{2}{\left(x \right)} \right)}}{2} + \frac{\sec^{2}{\left(x \right)}}{2}+ \mathrm{constant}


The answer is:

log(sec2(x))2+sec2(x)2+constant- \frac{\log{\left(\sec^{2}{\left(x \right)} \right)}}{2} + \frac{\sec^{2}{\left(x \right)}}{2}+ \mathrm{constant}

The graph
0.001.000.100.200.300.400.500.600.700.800.9005
The answer [src]
  1       1                  
- - + --------- + log(cos(1))
  2        2                 
      2*cos (1)              
log(cos(1))12+12cos2(1)\log{\left(\cos{\left(1 \right)} \right)} - \frac{1}{2} + \frac{1}{2 \cos^{2}{\left(1 \right)}}
=
=
  1       1                  
- - + --------- + log(cos(1))
  2        2                 
      2*cos (1)              
log(cos(1))12+12cos2(1)\log{\left(\cos{\left(1 \right)} \right)} - \frac{1}{2} + \frac{1}{2 \cos^{2}{\left(1 \right)}}
-1/2 + 1/(2*cos(1)^2) + log(cos(1))
Numerical answer [src]
0.597132940021366
0.597132940021366
The graph
Integral of tg^3(x) dx

    Use the examples entering the upper and lower limits of integration.