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cos^4(1/2x)

Integral of cos^4(1/2x) dx

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01cos4(x2)dx\int\limits_{0}^{1} \cos^{4}{\left(\frac{x}{2} \right)}\, dx
Detail solution
  1. Rewrite the integrand:

    cos4(x2)=(cos(x)2+12)2\cos^{4}{\left(\frac{x}{2} \right)} = \left(\frac{\cos{\left(x \right)}}{2} + \frac{1}{2}\right)^{2}

  2. There are multiple ways to do this integral.

    Method #1

    1. Rewrite the integrand:

      (cos(x)2+12)2=cos2(x)4+cos(x)2+14\left(\frac{\cos{\left(x \right)}}{2} + \frac{1}{2}\right)^{2} = \frac{\cos^{2}{\left(x \right)}}{4} + \frac{\cos{\left(x \right)}}{2} + \frac{1}{4}

    2. Integrate term-by-term:

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

        cos2(x)4dx=cos2(x)dx4\int \frac{\cos^{2}{\left(x \right)}}{4}\, dx = \frac{\int \cos^{2}{\left(x \right)}\, dx}{4}

        1. Rewrite the integrand:

          cos2(x)=cos(2x)2+12\cos^{2}{\left(x \right)} = \frac{\cos{\left(2 x \right)}}{2} + \frac{1}{2}

        2. Integrate term-by-term:

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

            cos(2x)2dx=cos(2x)dx2\int \frac{\cos{\left(2 x \right)}}{2}\, dx = \frac{\int \cos{\left(2 x \right)}\, dx}{2}

            1. Let u=2xu = 2 x.

              Then let du=2dxdu = 2 dx and substitute du2\frac{du}{2}:

              cos(u)4du\int \frac{\cos{\left(u \right)}}{4}\, du

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

                cos(u)2du=cos(u)du2\int \frac{\cos{\left(u \right)}}{2}\, du = \frac{\int \cos{\left(u \right)}\, du}{2}

                1. The integral of cosine is sine:

                  cos(u)du=sin(u)\int \cos{\left(u \right)}\, du = \sin{\left(u \right)}

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

              Now substitute uu back in:

              sin(2x)2\frac{\sin{\left(2 x \right)}}{2}

            So, the result is: sin(2x)4\frac{\sin{\left(2 x \right)}}{4}

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

            12dx=x2\int \frac{1}{2}\, dx = \frac{x}{2}

          The result is: x2+sin(2x)4\frac{x}{2} + \frac{\sin{\left(2 x \right)}}{4}

        So, the result is: x8+sin(2x)16\frac{x}{8} + \frac{\sin{\left(2 x \right)}}{16}

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

        cos(x)2dx=cos(x)dx2\int \frac{\cos{\left(x \right)}}{2}\, dx = \frac{\int \cos{\left(x \right)}\, dx}{2}

        1. The integral of cosine is sine:

          cos(x)dx=sin(x)\int \cos{\left(x \right)}\, dx = \sin{\left(x \right)}

        So, the result is: sin(x)2\frac{\sin{\left(x \right)}}{2}

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

        14dx=x4\int \frac{1}{4}\, dx = \frac{x}{4}

      The result is: 3x8+sin(x)2+sin(2x)16\frac{3 x}{8} + \frac{\sin{\left(x \right)}}{2} + \frac{\sin{\left(2 x \right)}}{16}

    Method #2

    1. Rewrite the integrand:

      (cos(x)2+12)2=cos2(x)4+cos(x)2+14\left(\frac{\cos{\left(x \right)}}{2} + \frac{1}{2}\right)^{2} = \frac{\cos^{2}{\left(x \right)}}{4} + \frac{\cos{\left(x \right)}}{2} + \frac{1}{4}

    2. Integrate term-by-term:

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

        cos2(x)4dx=cos2(x)dx4\int \frac{\cos^{2}{\left(x \right)}}{4}\, dx = \frac{\int \cos^{2}{\left(x \right)}\, dx}{4}

        1. Rewrite the integrand:

          cos2(x)=cos(2x)2+12\cos^{2}{\left(x \right)} = \frac{\cos{\left(2 x \right)}}{2} + \frac{1}{2}

        2. Integrate term-by-term:

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

            cos(2x)2dx=cos(2x)dx2\int \frac{\cos{\left(2 x \right)}}{2}\, dx = \frac{\int \cos{\left(2 x \right)}\, dx}{2}

            1. Let u=2xu = 2 x.

              Then let du=2dxdu = 2 dx and substitute du2\frac{du}{2}:

              cos(u)4du\int \frac{\cos{\left(u \right)}}{4}\, du

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

                cos(u)2du=cos(u)du2\int \frac{\cos{\left(u \right)}}{2}\, du = \frac{\int \cos{\left(u \right)}\, du}{2}

                1. The integral of cosine is sine:

                  cos(u)du=sin(u)\int \cos{\left(u \right)}\, du = \sin{\left(u \right)}

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

              Now substitute uu back in:

              sin(2x)2\frac{\sin{\left(2 x \right)}}{2}

            So, the result is: sin(2x)4\frac{\sin{\left(2 x \right)}}{4}

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

            12dx=x2\int \frac{1}{2}\, dx = \frac{x}{2}

          The result is: x2+sin(2x)4\frac{x}{2} + \frac{\sin{\left(2 x \right)}}{4}

        So, the result is: x8+sin(2x)16\frac{x}{8} + \frac{\sin{\left(2 x \right)}}{16}

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

        cos(x)2dx=cos(x)dx2\int \frac{\cos{\left(x \right)}}{2}\, dx = \frac{\int \cos{\left(x \right)}\, dx}{2}

        1. The integral of cosine is sine:

          cos(x)dx=sin(x)\int \cos{\left(x \right)}\, dx = \sin{\left(x \right)}

        So, the result is: sin(x)2\frac{\sin{\left(x \right)}}{2}

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

        14dx=x4\int \frac{1}{4}\, dx = \frac{x}{4}

      The result is: 3x8+sin(x)2+sin(2x)16\frac{3 x}{8} + \frac{\sin{\left(x \right)}}{2} + \frac{\sin{\left(2 x \right)}}{16}

  3. Add the constant of integration:

    3x8+sin(x)2+sin(2x)16+constant\frac{3 x}{8} + \frac{\sin{\left(x \right)}}{2} + \frac{\sin{\left(2 x \right)}}{16}+ \mathrm{constant}


The answer is:

3x8+sin(x)2+sin(2x)16+constant\frac{3 x}{8} + \frac{\sin{\left(x \right)}}{2} + \frac{\sin{\left(2 x \right)}}{16}+ \mathrm{constant}

The answer (Indefinite) [src]
  /                                        
 |                                         
 |    4/x\          sin(x)   sin(2*x)   3*x
 | cos |-| dx = C + ------ + -------- + ---
 |     \2/            2         16       8 
 |                                         
/                                          
sin(2x)2+x8+sinx2+x4{{{{\sin \left(2\,x\right)}\over{2}}+x}\over{8}}+{{\sin x}\over{2}} +{{x}\over{4}}
The graph
0.001.000.100.200.300.400.500.600.700.800.9002
The answer [src]
       3                                    
3   cos (1/2)*sin(1/2)   3*cos(1/2)*sin(1/2)
- + ------------------ + -------------------
8           2                     4         
sin2+8sin1+616{{\sin 2+8\,\sin 1+6}\over{16}}
=
=
       3                                    
3   cos (1/2)*sin(1/2)   3*cos(1/2)*sin(1/2)
- + ------------------ + -------------------
8           2                     4         
sin(12)cos3(12)2+3sin(12)cos(12)4+38\frac{\sin{\left(\frac{1}{2} \right)} \cos^{3}{\left(\frac{1}{2} \right)}}{2} + \frac{3 \sin{\left(\frac{1}{2} \right)} \cos{\left(\frac{1}{2} \right)}}{4} + \frac{3}{8}
Numerical answer [src]
0.852566581580553
0.852566581580553
The graph
Integral of cos^4(1/2x) dx

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