Answer:
A. 6 √2
Explanation:
If a triangle is a 45-45-90 triangle then,
Theorem 5-13: If each acute angle of a right triangle has a measure of
45 degrees, then the measure of the hypotenuse is the square root of two times as long as a leg (45, 45, 90 Theorem).
so the hypotenuse is x√2, and x = 6 (side length)