Answer:
x = 6
Step-by-step explanation:
A 45-45-90 isosceles right triangle has side lengths in the ratios ...
1 : 1 : √2
__
That is, the longest side (marked x in this figure) is √2 times the length of the other two equal-length sides.
x = (√2)×3√2 = 3×2
x = 6
