According to the Pythagorean Theorem, in a right triangle, the the squares of the sides equal the square of the hypotenuse. if the sides were to be A and B and the Hypotenuse were to b C, A²+B²=C². In your case, A=10 and C=10. If you were to plug that into the Pythagorean Theorem, 100+B²=100. (10²=100) If you subtract 100 by both sides (100=100 so they cancel each other out), B²=0. in a right triangle, a leg cannot equal 0. Therefore, A right triangle cannot have a leg that is 10 meters long and a hypotenuse that is 10 meters long.