We know that,
Area of the square = side of a square × side of a square
Since the area of a square is equal to the square of its side., the length of the side can be calculated by finding the square root of the area.
441 m2 = (side of a square)2
Side of a square = √441 = 21 m
The length of the side of a square whose area is 441 m2 is 21 m