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

1. ### 3uc1id

7
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. ### cristo

8,387
Staff Emeritus
Can you write sin(theta) in terms of sin(theta/2)?

3. ### sutupidmath

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. ### 3uc1id

7
ok tnx. i finally got it but at the end i integrated from 0~pi. to get it.