Using the areas of the sqaure and of the circle, it is found that the total area that is not reached by the sprinklers is of 343.36 ft².
What is the area of a square?
The area of a square of side length l is given by:
A = l²
In this problem, we have that l = 40 ft, hence:
A = (40 ft)² = 1600 ft².
What is the area of a circle?
The area of a circle of radius r is given by:
[tex]A = \pi r^2[/tex]
In this problem, we have four circles of radius r = 10 ft, hence it's combined area, in square feet, is given by:
[tex]A_c = 4\pi (10)^2 = 400\pi = 1256.64 \text{ft}^2[/tex]
The area not reached by the sprinklers is the subtraction of the area of the square by the area of the circle, hence:
1600 - 1256.64 = 343.36 ft².
More can be learned about the area of a rectangle at https://brainly.com/question/10489198