Pythagorean Triples

Just wanted to share something new with all of you which I found while
browsing through
Wikipedia (http://en.wikipedia.org/wiki/Pythagorean_triple), I found
following link: http://vcpandya.googlepages.com/pythagoreantriples

It gives formula to find all Pythagorean Triples based on a given
side.

I wonder why there is no proof given on that site. Anyways I gave it a
try, but could not get it. :)

.