Answer :
You can draw it out
Make a right triangle from the square
Diagonal length = hypothenuse
Use Pythagorean theorem as stated
a^2 + b^2 = c^2
32^2 + b^2 = 40^2
1024 + b^2 = 1600
b^2 = 576
Square root of 576 = 24
Solution: the width is 24 inches
Make a right triangle from the square
Diagonal length = hypothenuse
Use Pythagorean theorem as stated
a^2 + b^2 = c^2
32^2 + b^2 = 40^2
1024 + b^2 = 1600
b^2 = 576
Square root of 576 = 24
Solution: the width is 24 inches
