We are given a cube of side 3 ft and we are asked to determine its surface area. The surface area of a cube is 6 times the area of one of its faces. The area of its faces is the side squared, therefore, the total surface area is:
[tex]S=6l^2[/tex]Where:
[tex]l=\text{ length of the side }[/tex]Now, we plug in the value of the side:
[tex]S=6(3ft)^2[/tex]Solving the operations:
[tex]S=54ft^2[/tex]Therefore, the surface area is 54 square feet.