The strenghth of a wooden beam with a rectangular cross section and fixed length is proportional to the product of its width and the square of its height where the proportionailty constant is 2 psi.

Suppose the roofing company wants to make wooden beams of fixed length with rectangular cross sections from logs that are 4 inches in diameter. If the height of each beam must be at least 3.5 inches find the dimesnsions of the strongest beams.