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Integral of xcos((x-pi)/3) dx

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  1                 
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 |       /x - pi\   
 |  x*cos|------| dx
 |       \  3   /   
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01xcos(xπ3)dx\int\limits_{0}^{1} x \cos{\left(\frac{x - \pi}{3} \right)}\, dx
Integral(x*cos((x - pi)/3), (x, 0, 1))
Detail solution
  1. Use integration by parts:

    udv=uvvdu\int \operatorname{u} \operatorname{dv} = \operatorname{u}\operatorname{v} - \int \operatorname{v} \operatorname{du}

    Let u(x)=xu{\left(x \right)} = x and let dv(x)=sin(x3+π6)\operatorname{dv}{\left(x \right)} = \sin{\left(\frac{x}{3} + \frac{\pi}{6} \right)}.

    Then du(x)=1\operatorname{du}{\left(x \right)} = 1.

    To find v(x)v{\left(x \right)}:

    1. Let u=x3+π6u = \frac{x}{3} + \frac{\pi}{6}.

      Then let du=dx3du = \frac{dx}{3} and substitute 3du3 du:

      3sin(u)du\int 3 \sin{\left(u \right)}\, du

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

        sin(u)du=3sin(u)du\int \sin{\left(u \right)}\, du = 3 \int \sin{\left(u \right)}\, du

        1. The integral of sine is negative cosine:

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

        So, the result is: 3cos(u)- 3 \cos{\left(u \right)}

      Now substitute uu back in:

      3cos(x3+π6)- 3 \cos{\left(\frac{x}{3} + \frac{\pi}{6} \right)}

    Now evaluate the sub-integral.

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

    (3cos(x3+π6))dx=3cos(x3+π6)dx\int \left(- 3 \cos{\left(\frac{x}{3} + \frac{\pi}{6} \right)}\right)\, dx = - 3 \int \cos{\left(\frac{x}{3} + \frac{\pi}{6} \right)}\, dx

    1. Let u=x3+π6u = \frac{x}{3} + \frac{\pi}{6}.

      Then let du=dx3du = \frac{dx}{3} and substitute 3du3 du:

      3cos(u)du\int 3 \cos{\left(u \right)}\, du

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

        cos(u)du=3cos(u)du\int \cos{\left(u \right)}\, du = 3 \int \cos{\left(u \right)}\, du

        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: 3sin(u)3 \sin{\left(u \right)}

      Now substitute uu back in:

      3sin(x3+π6)3 \sin{\left(\frac{x}{3} + \frac{\pi}{6} \right)}

    So, the result is: 9sin(x3+π6)- 9 \sin{\left(\frac{x}{3} + \frac{\pi}{6} \right)}

  3. Add the constant of integration:

    3xcos(x3+π6)+9sin(x3+π6)+constant- 3 x \cos{\left(\frac{x}{3} + \frac{\pi}{6} \right)} + 9 \sin{\left(\frac{x}{3} + \frac{\pi}{6} \right)}+ \mathrm{constant}


The answer is:

3xcos(x3+π6)+9sin(x3+π6)+constant- 3 x \cos{\left(\frac{x}{3} + \frac{\pi}{6} \right)} + 9 \sin{\left(\frac{x}{3} + \frac{\pi}{6} \right)}+ \mathrm{constant}

The answer (Indefinite) [src]
  /                                                      
 |                                                       
 |      /x - pi\               /x   pi\          /x   pi\
 | x*cos|------| dx = C + 9*sin|- + --| - 3*x*cos|- + --|
 |      \  3   /               \3   6 /          \3   6 /
 |                                                       
/                                                        
xcos(xπ3)dx=C3xcos(x3+π6)+9sin(x3+π6)\int x \cos{\left(\frac{x - \pi}{3} \right)}\, dx = C - 3 x \cos{\left(\frac{x}{3} + \frac{\pi}{6} \right)} + 9 \sin{\left(\frac{x}{3} + \frac{\pi}{6} \right)}
The graph
0.001.000.100.200.300.400.500.600.700.800.9005
The answer [src]
  9        /1   pi\        /1   pi\
- - - 3*cos|- + --| + 9*sin|- + --|
  2        \3   6 /        \3   6 /
923cos(13+π6)+9sin(13+π6)- \frac{9}{2} - 3 \cos{\left(\frac{1}{3} + \frac{\pi}{6} \right)} + 9 \sin{\left(\frac{1}{3} + \frac{\pi}{6} \right)}
=
=
  9        /1   pi\        /1   pi\
- - - 3*cos|- + --| + 9*sin|- + --|
  2        \3   6 /        \3   6 /
923cos(13+π6)+9sin(13+π6)- \frac{9}{2} - 3 \cos{\left(\frac{1}{3} + \frac{\pi}{6} \right)} + 9 \sin{\left(\frac{1}{3} + \frac{\pi}{6} \right)}
-9/2 - 3*cos(1/3 + pi/6) + 9*sin(1/3 + pi/6)
Numerical answer [src]
0.338258415318288
0.338258415318288

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