# I forgot how to do this integration Help

1. Jul 5, 2011

### Karmerlo

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

Do the integration

2. Relevant equations

3. The attempt at a solution

I forgot how to do this integration with another method. I think I can do it through Trigonometric Method. But I remember that there is still another way to do it without using Trigonometric Method. Anyone can show me steps to do it? Thanks.

2. Jul 5, 2011

### Clever-Name

Well, for the trig method you would use the substitution let x = ytan(u)
If that gets you the right answer then why bother with another method. I can't think of a different method right now that would work.

3. Jul 5, 2011

### SammyS

Staff Emeritus
Take the derivative of $\displaystyle \frac{x}{y^2\sqrt{x^2+y^2}}\,,$ treating y as a constant, of course. Then see if you can reverse the process.

4. Jul 5, 2011

### dextercioby

Try a substitution $x=y \sinh t$. The resulting integration will be trivial.