A 45-45-90 triangle follows a unique pattern. It has two congruent sides and one side that = x * sqrt(2).
If AC = 9sqrt(2), then AB is also 9sqrt(2).
To find CB, we need to multiply 9sqrt(2) by sqrt(2).
9sqrt(2) * sqrt(2) = 9 * 2 = 18
CB = 18
Hope this helps!