Pythagoras

What I need to write to use Pythagoras' theorem like an expression? Or there is an alternative expression in system/math?

<img src="http://dl.dropbox.com/u/472186/Construct/Forums/Irudiak/pitagoras.jpg">

2 ways:

1) System expression "sqrt"

sqrt(a^2 + b^2)

2) System expression "distance" (which is using that theorem)

distance(x1, y1, x2, y2)

Thanks tulamide!