For this case we have to:
Let "a" be the side of the square. Then, the area "A", will be given by:
[tex]A = a * a = a ^ 2[/tex]
Also, by the Pythagorean theorem we have to:
[tex]x ^ 2 = a ^ 2 + a ^ 2\\x ^ 2 = 2a ^ 2\\\frac {x ^ 2} {2} = a ^ 2[/tex]
Finally the area is:
[tex]A = \frac {x ^ 2} {2}[/tex]
Answer:
Option A
