The surface area, SA, of a rectangular prism is given by the formula:
SA = 2ab + 2bc + 2ac,
where, a, b, and c are lengths of the 3 sides of the rectangular prism
For this problem, the surface area of the rectangular prism was given to be 208 cm². The two sides given can be assigned the variables, a = 2 cm and b = 10 cm. This leaves us with one side, c, as the unknown dimension. The resulting equation is as follows:
208 cm² = 2(2 cm)(10 cm) + 2(10 cm)(c) + 2(2 cm)(c)
c = 7 cm