# Triangle that has the hypo as √(u^2 +1)

1. Sep 26, 2013

### Jbreezy

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

If I have a triangle that has the hypo as √(u^2 +1)
adj as 1 and oppo as u
I did an integral with trig sub. So I used

2. Relevant equations

u = tan(θ)

3. The attempt at a solution
At the end of my integral I ended up with an expression (1/4)sin(2θ)
When I substitute back in to the integral for theta. I will get (1/2)(u/(sqrt(u^2 +1))
right? How does back sub work if you have 2(theta)

2. Sep 26, 2013

### vela

Staff Emeritus
Use $\sin 2\theta = 2 \sin \theta \cos \theta$. You need the trig functions in terms of $\theta$, not $2\theta$.

3. Sep 26, 2013

### Jbreezy

Always like this? With double angle?

4. Sep 26, 2013

### vela

Staff Emeritus
Could you please use complete sentences? I'm not sure what you're asking.

5. Sep 26, 2013

### Jbreezy

Nevermind thx