# Homework Help: Integration help please [solved]

1. Feb 7, 2010

### holezch

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

$$\int \frac{1}{\sqrt{a^{2} + x^{2}}}$$

2. Relevant equations

3. The attempt at a solution

I got:

$$\int \frac{1}{\sqrt{a^{2} + x^{2}}} = \sqrt{c} \ast \int \frac{1}{\sqrt{c \ast{x^{2}} + 1}}$$

$$\frac{1}{a^{2}} = c$$

NEVERMIND! I got it: I couldn't remember the integral of arcsin..
so it's

$$\frac{1}{a} = c$$

$$c \ast \int \frac{1}{\sqrt{c \ast{x^{2}} + 1}} = c \ast arcsin(cx) /c$$

Last edited: Feb 7, 2010
2. Feb 8, 2010

### Ratio Test =)

This is not an arcsine integral.
Try $$x=a \,\ tan(\theta)$$.