In a right triangle, the hypotenuse is always the longest side. Plus, the hypotenuse squared has to equal the sum of the squares of the other 2 sides. For the first "triangle" above: does [tex]14 ^{2} =5 ^{2} +4 ^{2} [/tex]? Let's check. 196 = 25 + 16 so does 196 = 41? Obviously not. So that is not a right triangle. Let's check the second one the same way. Does [tex]5 ^{2} =3 ^{2} +4 ^{2} [/tex]? 25 = 9 + 16. Does 25 = 25? Of course it does! So 1 is not a right triangle, but 2 is!
