this is a square. because the lengths and the widths are equal. I mean, all four sides are equal.
the area of a square is the square of a side
[tex] {s}^{2} = {5.4}^{2} = 29.16[/tex]
and the perimeter of a square is a side multiplied by 4
[tex]4s = 4 \times 5.4 = 21.6[/tex]
hope this helps
good luck