By definition a square has all 4 sides equal, the area of a square is sxs or s^2, so s^2 = 400, s = square root of 400 = 20. All sides will be equal to 20 m. The perimeter is the sum of the sides or 4 x s or 80.
Steps:
A= L^2
Where L is length of the side
400=L^2 》》》》》 square root
L= 20 all sides of square are 20 m
P = 4L
=4(20)
=80m
