<h3>
Answer: The other two sides are 4 inches each</h3>
Rule: If x is the leg of a 45-45-90 triangle, then x*sqrt(2) is the hypotenuse.
We can prove this by showing that x^2+x^2 = (x*sqrt(2))^2 is an identity. It's from the pythagorean theorem a^2+b^2 = c^2.
Put another way, if we know that a = x and b = x are the two congruent legs, then x^2+x^2 = c^2 leads to c = x*sqrt(2). This triangle is known as an isosceles right triangle.
So if 4*sqrt(2) is the hypotenuse, we match that up with the template x*sqrt(2) and see that x = 4 must be the case.
