Let's suppose that the dashed line bisect the right angle and the figure is a square. Then, we can draw the following picture
then, we can draw the following right triangle
and we need to find x. This can be done as
then x is equal to
since cos 45 is
then, x is given by
We can note that the length of one side of our square is
so, the one side is equal to
Since the area of a square is
the area of our figure is equal to
That is, the area of the square is equal to 128 centimeters squared.