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

  1. The title says it all. im trying to integrate that but im 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
     
  2. jcsd
  3. cristo

    cristo 8,394
    Staff Emeritus
    Science Advisor

    Can you write sin(theta) in terms of sin(theta/2)?
     
  4. 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??
     
  5. ok tnx. i finally got it but at the end i integrated from 0~pi. to get it.
     
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