# Calculus 2: Trigonometric Substitution, using Z = tan(x/2)

1. Oct 18, 2009

### kiz

1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

After substituting:

Using

I'm stuck here:

2. Oct 18, 2009

### twasnow

I am so glad I have no need to remember any of this. my computer does all the calculations for me :)

3. Oct 18, 2009

### Dick

http://en.wikipedia.org/wiki/Tangent_half-angle_formula You seem to have turned a '2' into a 'z' in you dx derivation. And you would have to change the limits to 'z' limits instead of 'x' limits if you are going to stick with the variable z. Otherwise just find the indefinite integral in terms of z and change the function back to x.

4. Oct 18, 2009

### kiz

Okay, thanks for the help, I'm looking at the solution and it has $$1$$ and $$\sqrt{3}$$ for the bounds, but I do not get that when insert $$\frac{\pi}{3}$$ and $$\frac{\pi}{2}$$.

EDIT:

I got it, guess im blind. Thanks again.

Last edited: Oct 18, 2009