Integral of Sin(theta)/Sin(theta/2)

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In summary, the conversation revolves around finding a substitution for sin(theta) in terms of sin(theta/2) in order to integrate a function. Suggestions are given and the double angle formula for sin is used to solve the problem. The conversation also mentions integrating from 0 to pi to get the final solution.
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3uc1id
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The title says it all. I am trying to integrate that but I am not sure what substitution to use. i tried u=cos(theta/2) but something is not coming out right. does anyone have any suggestions? they would be well appriciated. thanks
 
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  • #2
Can you write sin(theta) in terms of sin(theta/2)?
 
  • #3
well, since thw OP hasn't shown up yet, i am going to make it a little bit easier for him.
Like cristo suggested you need to write sin(theta) in terms of sin(theta/2)
notice that sin(theta)=sin(2(theta/2)), now applying the double angle forumula for sin, what do we get?? like sin(x+y) = sin(x)cos(y)+cos(x)sin(y), now apply the same thing here, just notice that in our case we have x=y. Can you go from here??
 
  • #4
ok tnx. i finally got it but at the end i integrated from 0~pi. to get it.
 

1. What is the formula for the integral of Sin(theta)/Sin(theta/2)?

The formula for the integral of Sin(theta)/Sin(theta/2) is ∫ Sin(theta)/Sin(theta/2) d(theta) = 2*Sin(theta/2) + C, where C is a constant.

2. How do you solve the integral of Sin(theta)/Sin(theta/2)?

To solve the integral of Sin(theta)/Sin(theta/2), you can use the substitution method. Let u = Sin(theta/2), then d(theta) = 2cos(theta/2) d(theta/2). Substituting these into the integral, we get ∫ Sin(theta)/Sin(theta/2) d(theta) = ∫2u d(u) = 2u^2 + C = 2*Sin^2(theta/2) + C. Finally, substitute back u = Sin(theta/2) to get the final solution: 2*Sin^2(theta/2) + C.

3. What is the domain of the integral of Sin(theta)/Sin(theta/2)?

The domain of the integral of Sin(theta)/Sin(theta/2) is all real numbers except for multiples of pi, as this would cause a division by zero error.

4. How can the integral of Sin(theta)/Sin(theta/2) be used in applications?

The integral of Sin(theta)/Sin(theta/2) can be used in applications involving wave phenomena, such as in physics and engineering. It can also be used in calculating the area under a curve in trigonometric functions.

5. Can the integral of Sin(theta)/Sin(theta/2) be simplified further?

Yes, the integral of Sin(theta)/Sin(theta/2) can be further simplified using trigonometric identities. For example, using the double angle identity for sine, we can rewrite the integral as ∫ Sin(theta)/Sin(theta/2) d(theta) = ∫2*Sin(theta/2)*Cos(theta/2) d(theta) = ∫2*Sin(theta/2)*Sin(pi - theta/2) d(theta). Then using the product-to-sum formula, we get ∫2*Sin(theta/2)*Sin(pi - theta/2) d(theta) = ∫(Cos(theta) - Cos(pi - theta)) d(theta) = Sin(theta) + Sin(pi - theta) + C = Sin(theta) + Sin(theta) + C = 2*Sin(theta) + C. This is equivalent to the previously mentioned solution of 2*Sin(theta/2) + C.

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