Answer:
[tex]\textbf{A. }4\sqrt{6}[/tex]
Step-by-step explanation:
The hypotenuse of the isosceles right triangle is √2 times the length of one leg, so is 6√2.
The hypotenuse of the 30°-60°-90° right triangle is 2/√3 times the length of the longer leg.
[tex]x=\dfrac{2}{\sqrt{3}}\cdot 6\sqrt{2}\\\\=\dfrac{(2\sqrt{3})(6\sqrt{2})}{3}\quad\text{rationalize the denominator}\\\\\boxed{x=4\sqrt{6}}[/tex]