So from the problem we get that the two sides of the rctangle are 16 cm 12 cm which are base perpendicular of the right angle triangle. H = 20 cm. So the diagonal of the rectangle = 20 cm.
The area of the deck is : A ( deck ) = 8 * 27.63 = 221.04 ft² The area of the sheet of wood: A ( sheet ) = 4 * 8 = 32 ft² 221.04 : 32 = 6.9 ≈ 7 ( we need a whole number ) Answer: He should buy 7 sheets of wood to cover the surface of the deck.