In a 45-45-90 triangle, what is the length of the hypotenuse if the length of one of the legs is 5 in.?

You could use the Pythagorean Theorem to find this. Since the two legs will be the same length:

5² + 5² = c²

25 + 25 = c²

50 = c²

√50 = √c²

5√2 = c

so the hypotenuse length is 5√2