# Integral from 0 to 1 of 1/sqrt(1+x^2)

## Homework Statement

$$\int_0^1 \frac{1}{\sqrt{x^2+1}}\,dx$$

## Homework Equations

Integration by substitution looks like it might help here...

## The Attempt at a Solution

The answer is $$\log (1+\sqrt 2)$$, but I'm at a loss as to how to derive that.

You could try a trig substitution such as $x=tan\theta$.Hyperbolic trig sub. would be possible as well.