The dinning table in the kitchen has a length of 2.3 m & a width of 3 m. Find the area of a sheet that will cover the table top

Aconstruction worker needs to put a rectangular window in the side of a building he knows from measuring that the top and bottom of the window have a width of 8bfeet and the sides have a length of 15 feet he also measured one diagonal to be 17 feet what is the length of the other diagonal