Hello from MrBillDoesMath!
Answer:
31.96 (approximately)
Discussion:
Suppose the square has side length "x". Then from Pythagoras,
x^2 + x^2 = (11.3)^2 => (where 11.3 is the length of the hypotenuse)
2x^2 = 127.69 => (divide both sides by 2)
x^2 = 127.69/2 =>
x^2 = 63.845 => (take the square root of each side)
x = 7.99
Perimeter of the square = 4x
= 4(7.99) = 31.96
Thank you,
MrB