To cover the entirety of the cushion, we will have to cover all 6 sides of the cushion. We are looking for the surface area of the cushion.
The top:
12 x 14 = 168in^2
The bottom:
12 x 14 = 168in^2
The 2 long sides:
14 x 3 = 42in^2 (each)
The 2 short sides:
12 x 3 = 36in^2 (each)
If we add up all of the areas:
168 + 168 + 42 + 42 + 36 + 36 = 492in^2
Therefore we will need 492 square inches of fabric to cover the cushion.
