Answer:
12
Step-by-step explanation:
The figure is an equilateral righ triangle - or if you prefer, it's half a square.
As a triangle: x is the ipotenuse, pythagorean theorem
[tex]x^2 = (6\sqrt2)^2 + (6\sqrt2)^2\\x^2 = 72+72 = 144 \rightarrow x = 12[/tex]
As half a square: diagonal is [tex]\sqrt2[/tex] times the side
x= [tex](\sqrt2) (6\sqrt2) = 2\times6 = 12[/tex]
