Respuesta :

The length of a diagonal of a square is the side*sqrt(2). Let's call one side of the square: s


So we have 18 = s*sqrt(2)

18/sqrt(2) = s


18sqrt(2)/2 = s


9sqrt(2) = s


Since the perimeter is 4 sides we multiply by 4 to get 36sqrt(2) as the perimeter.