How to integrate cos( sin(x) ) from 0 to pi

In summary, the formula for integrating cos(sin(x)) from 0 to pi is ∫ cos(sin(x)) dx = −0.5 ∫ (e^x + e^(-x)) sin(x) dx. To solve this integral, the substitution method can be used by letting u = sin(x), and then using the trigonometric identity cos(u) = sin(u + π/2). The power rule cannot be used for this integral because cos(sin(x)) is an oscillating function. However, there is a trick to integrate it, by using the trigonometric identity cos(sin(x)) = sin(x + π/2) and then using the substitution method with u = x + π/2. It is
  • #1
dirk_mec1
761
13

Homework Statement



[tex]
\int_{0}^{\pi} \cos ( \sin x ) \mbox{d}x
[/tex]

The Attempt at a Solution



If I use [itex]u = \pi-x [/itex] I get :
[tex]
\int_{0}^{\pi} \cos ( \sin x ) \mbox{d}x = \int_{0}^{\pi} \sin ( \cos x ) \mbox{d}x
[/tex]

but then what?
 
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  • #2


That reminds me of a definition of the Bessel function in terms of integrals...
 
  • #3


So n = 0 here:

[tex] J_n(x) = \frac{1}{\pi} \int_{0}^{\pi} \cos (n \tau - x \sin \tau) \,\mathrm{d}\tau. [/tex]
 
  • #4


dirk_mec1 said:
So n = 0 here:

[tex] J_n(x) = \frac{1}{\pi} \int_{0}^{\pi} \cos (n \tau - x \sin \tau) \,\mathrm{d}\tau. [/tex]

Sure. n=0, x=1.
 

Related to How to integrate cos( sin(x) ) from 0 to pi

1. What is the formula for integrating cos(sin(x)) from 0 to pi?

The formula for integrating cos(sin(x)) from 0 to pi is ∫ cos(sin(x)) dx = −0.5 ∫ (e^x + e^(-x)) sin(x) dx.

2. How do I solve the integral of cos(sin(x)) from 0 to pi?

To solve the integral of cos(sin(x)) from 0 to pi, you can use the substitution method by letting u = sin(x). This will transform the integral into ∫ cos(u) du which can be easily solved using the trigonometric identity cos(u) = sin(u + π/2).

3. Can I use the power rule to integrate cos(sin(x)) from 0 to pi?

No, you cannot use the power rule to directly integrate cos(sin(x)) from 0 to pi. This is because cos(sin(x)) is an oscillating function and does not have a constant derivative.

4. Is there a shortcut or trick to integrate cos(sin(x)) from 0 to pi?

Yes, there is a trick to integrate cos(sin(x)) from 0 to pi. You can use the trigonometric identity cos(sin(x)) = sin(x + π/2) to rewrite the integral as ∫ sin(x + π/2) dx. Then, using the substitution method with u = x + π/2, the integral can be easily solved.

5. Why is it important to specify the limits of integration when solving the integral of cos(sin(x))?

Specifying the limits of integration is important because it helps to determine the exact area under the curve of cos(sin(x)) from 0 to pi. Without specifying the limits, the integral would result in an indefinite integral with a constant of integration, making it impossible to find the exact value.

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