Between the big square and the small square are four small squares with a side length of 2 cm and four rectangles with a length of 40 cm and a width of 2 cm.

So the area of the big square is 40+4× 2× 2+4× 2×√ 40.

=40+ 16+8√40

=56+8√40

=56+ 16√ 10

Therefore, the area of a big square is 56+8√ 10 square centimeter.

The answers upstairs are all a mess. Ha ha ha ha ha ha ha