The cross section is a rectangle, so its area formula is: Area = length * width.
If you look, the width is the diagonal of the side of the cube; thus, you can use Pythagorean theorem to find its measurement: a^2 + b^2 = c^2 → 5^2 + 5^2 = c^2 →
50 = c^2 → c = √(50)
Now, use the area formula and get: Area = 5 * √(50) = 5√(50) = 35.36 m^2 :)
