Now, let and it falls right into place.
Here's another one for you folks:
I have no idea which trigonometric identity to use... could you guys give me an idea.
I feel like the only one might possibly be [tex] sin(x)cos(y) = 1/2(sin(x+y) + sin(x-y)) but I don't feel like this is the right one.
Please tell me I'm not just over thinking it... could you do this? I'm also 100% sure you couldn't do this but just making sure.
equals ?
Close, but not quite. You can't take the integral of with respect to . So, since we substituted for , you also need to get rid of and for something in terms of .
We know:
So, take the derivative of that to get:
Then finish your substitution, and you'll be ready to integrate.
You're making the same mistake you did before. Recall your first substitution:
That was correct! But you still need to do more; you need to either *completely* evaluate the integral in terms of (and you can't do that), or *completely* evaluate the integral in terms of .
In other words, you need to get rid of all and terms.
Ok so, tell me if I'm doing this right then...
equals:
let so so
this all equals:
both of the cos(x)'s cancel each other out so your left with:
equals:
then replace the u's with sin(x)...
final answer:
and if you wanted to make it look a little nicer...
I hope this is right or else I'm done with haha.