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tg^3xdx/cos^2x

Integral of tg^3xdx/cos^2x dx

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01tan3(x)11cos2(x)dx\int\limits_{0}^{1} \tan^{3}{\left(x \right)} 1 \cdot \frac{1}{\cos^{2}{\left(x \right)}}\, dx
Integral(tan(x)^3*1/cos(x)^2, (x, 0, 1))
Detail solution
  1. Rewrite the integrand:

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

      (u212)du\int \left(\frac{u}{2} - \frac{1}{2}\right)\, du

      1. Integrate term-by-term:

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

          u2du=udu2\int \frac{u}{2}\, du = \frac{\int u\, du}{2}

          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}

          So, the result is: u24\frac{u^{2}}{4}

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

          (12)du=u2\int \left(- \frac{1}{2}\right)\, du = - \frac{u}{2}

        The result is: u24u2\frac{u^{2}}{4} - \frac{u}{2}

      Now substitute uu back in:

      sec4(x)4sec2(x)2\frac{\sec^{4}{\left(x \right)}}{4} - \frac{\sec^{2}{\left(x \right)}}{2}

    Method #2

    1. Rewrite the integrand:

      (sec2(x)1)tan(x)sec2(x)=tan(x)sec4(x)tan(x)sec2(x)\left(\sec^{2}{\left(x \right)} - 1\right) \tan{\left(x \right)} \sec^{2}{\left(x \right)} = \tan{\left(x \right)} \sec^{4}{\left(x \right)} - \tan{\left(x \right)} \sec^{2}{\left(x \right)}

    2. Integrate term-by-term:

      1. Let u=sec4(x)u = \sec^{4}{\left(x \right)}.

        Then let du=4tan(x)sec4(x)dxdu = 4 \tan{\left(x \right)} \sec^{4}{\left(x \right)} dx and substitute du4\frac{du}{4}:

        116du\int \frac{1}{16}\, du

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

          14du=1du4\int \frac{1}{4}\, du = \frac{\int 1\, du}{4}

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

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

          So, the result is: u4\frac{u}{4}

        Now substitute uu back in:

        sec4(x)4\frac{\sec^{4}{\left(x \right)}}{4}

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

        (tan(x)sec2(x))dx=tan(x)sec2(x)dx\int \left(- \tan{\left(x \right)} \sec^{2}{\left(x \right)}\right)\, dx = - \int \tan{\left(x \right)} \sec^{2}{\left(x \right)}\, dx

        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}:

          14du\int \frac{1}{4}\, du

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

            12du=1du2\int \frac{1}{2}\, du = \frac{\int 1\, du}{2}

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

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

            So, the result is: u2\frac{u}{2}

          Now substitute uu back in:

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

        So, the result is: sec2(x)2- \frac{\sec^{2}{\left(x \right)}}{2}

      The result is: sec4(x)4sec2(x)2\frac{\sec^{4}{\left(x \right)}}{4} - \frac{\sec^{2}{\left(x \right)}}{2}

    Method #3

    1. Rewrite the integrand:

      (sec2(x)1)tan(x)sec2(x)=tan(x)sec4(x)tan(x)sec2(x)\left(\sec^{2}{\left(x \right)} - 1\right) \tan{\left(x \right)} \sec^{2}{\left(x \right)} = \tan{\left(x \right)} \sec^{4}{\left(x \right)} - \tan{\left(x \right)} \sec^{2}{\left(x \right)}

    2. Integrate term-by-term:

      1. Let u=sec4(x)u = \sec^{4}{\left(x \right)}.

        Then let du=4tan(x)sec4(x)dxdu = 4 \tan{\left(x \right)} \sec^{4}{\left(x \right)} dx and substitute du4\frac{du}{4}:

        116du\int \frac{1}{16}\, du

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

          14du=1du4\int \frac{1}{4}\, du = \frac{\int 1\, du}{4}

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

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

          So, the result is: u4\frac{u}{4}

        Now substitute uu back in:

        sec4(x)4\frac{\sec^{4}{\left(x \right)}}{4}

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

        (tan(x)sec2(x))dx=tan(x)sec2(x)dx\int \left(- \tan{\left(x \right)} \sec^{2}{\left(x \right)}\right)\, dx = - \int \tan{\left(x \right)} \sec^{2}{\left(x \right)}\, dx

        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}:

          14du\int \frac{1}{4}\, du

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

            12du=1du2\int \frac{1}{2}\, du = \frac{\int 1\, du}{2}

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

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

            So, the result is: u2\frac{u}{2}

          Now substitute uu back in:

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

        So, the result is: sec2(x)2- \frac{\sec^{2}{\left(x \right)}}{2}

      The result is: sec4(x)4sec2(x)2\frac{\sec^{4}{\left(x \right)}}{4} - \frac{\sec^{2}{\left(x \right)}}{2}

  3. Now simplify:

    (sec2(x)2)sec2(x)4\frac{\left(\sec^{2}{\left(x \right)} - 2\right) \sec^{2}{\left(x \right)}}{4}

  4. Add the constant of integration:

    (sec2(x)2)sec2(x)4+constant\frac{\left(\sec^{2}{\left(x \right)} - 2\right) \sec^{2}{\left(x \right)}}{4}+ \mathrm{constant}


The answer is:

(sec2(x)2)sec2(x)4+constant\frac{\left(\sec^{2}{\left(x \right)} - 2\right) \sec^{2}{\left(x \right)}}{4}+ \mathrm{constant}

The answer (Indefinite) [src]
  /                                            
 |                               2         4   
 |    3         1             sec (x)   sec (x)
 | tan (x)*1*------- dx = C - ------- + -------
 |              2                2         4   
 |           cos (x)                           
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/                                              
2sin2x14sin4x8sin2x+4{{2\,\sin ^2x-1}\over{4\,\sin ^4x-8\,\sin ^2x+4}}
The graph
0.001.000.100.200.300.400.500.600.700.800.9020-10
The answer [src]
             2   
1   1 - 2*cos (1)
- + -------------
4          4     
      4*cos (1)  
14sin418sin21+4+sin212sin414sin21+2+14-{{1}\over{4\,\sin ^41-8\,\sin ^21+4}}+{{\sin ^21}\over{2\,\sin ^41 -4\,\sin ^21+2}}+{{1}\over{4}}
=
=
             2   
1   1 - 2*cos (1)
- + -------------
4          4     
      4*cos (1)  
14+12cos2(1)4cos4(1)\frac{1}{4} + \frac{1 - 2 \cos^{2}{\left(1 \right)}}{4 \cos^{4}{\left(1 \right)}}
Numerical answer [src]
1.47078538753166
1.47078538753166
The graph
Integral of tg^3xdx/cos^2x dx

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