Answer:
A
Explanation:
A cube has 6 square faces
given surface area = 54 mm² , then
area of one face = 54 mm² ÷ 6 = 9 mm²
the area (A) of a square is calculated as
A = s² ( s is the side length ) , so
s² = 9 ( take square root of both sides )
s =
= 3 mm