Can someone me with this question ?

  36 ft²

Step-by-step explanation:

If BE = 3√2 ft, then the diagonal BD is 6√2 ft. The area of the square (as with any rhombus) is half the product of the diagonals. Since both diagonals are the same length, the area of the square is ...

  area = 1/2·(6√2 ft)² = 36 ft²

The area of the square is 36 square feet.

You may be expected to find the length of one side of the square using the Pythagorean theorem.

  AB² = AE² + EB² . . . . . = the area of the square

  AB² = (3√2 ft)² +(3√2 ft)² = 18 ft² + 18 ft²

  AB² = 36 ft² . . . . . . . . . the area of the square