What is the missing side length?

In a 45-45-90 triangle, the legs are equal and the hypotenuse is sqrt2 times longer than either leg

y (leg) = 5 rt 2 / 2

x (hyp) = 5 rt 2 / 2 x rt 2
= 5 * rt 2 * rt 2 / 2
= 5 * 2 / 2
= 10/2
x = 5

Its a right angled triangle not a right triangle

Ithink the answer is a.3: 1i hope this