i have no clue how to do this can you please show the steps?

Let's consider the information at hand:
⇒ has some special property about its side length
⇒ look at the diagram I attached
Using the same ratios of side length as seen in the diagram:
⇒ we get the equation:
[tex]\frac{1}{\frac{\sqrt{2} }{2} } =\frac{x}{3\sqrt{2} } \\\frac{\sqrt{2} }{2}*x=3\sqrt{2} \\\frac{x}{2}=3\\ x=3*2\\x=6[/tex]
Thus x = 6.
Answer: x = 6
Hope that helps!