For example, if one of the other sides has a length of 3 meters (when squared, 9 m²) and the other has a length of 4 m (when squared, 16 m²). Their squares add up to 25 m². The length of the hypotenuse is the square root of this, or 5 m.
The word hypotenuse derives, according to some sources, from the Greek ὑποτείνουσα (hypoteinousa), a combination of hypo- ("under") and teinein ("to stretch") . Others suggest the original meaning in Ancient Greek was for a thing which supports something in the manner of a prop or butress dervived from a combination of hypo- ("under") and tenuse ("side").