If a triangle has two equal legs (the smaller sides) then the leg times the square root of two equals the hypotenuse. For example, a leg length is 5. So the hypotenuse equals 5 times the square root of two. Or you could use the Pythagorean theorem. 5 squared plus 5 squared equals 50. Then find the square root of 50. Which is an ugly number. 5 times the square root of two equals the square root 50. Why well you have to turn 5 into a square root. So you turn it into the square root of 25. You can times a root by a root. 25 times 2 equals the square root of 50.