D . <span>He determined the formula for finding the hypotenuse of a right triangle.</span>
The United States is stronger than all those countries combine
because long ago every country that we know of now was once one whole continent. Since then we have had a lot of natural and human disasters happen that have changed the earth.
natural disasters
ex: volcano's, hurricanes, tornados, earth quakes
human disasters
ex: wars. duh!