To make room for the new baby, Glenn is adding a room to his house. The blueprints for the addition indicate that the room should be a rectangle with dimensions of 12 ft wide by 16 ft long. Glenn just finished the framing and wants to make sure the room is a perfect rectangle before he starts putting up the drywall. To do this he measures the diagonals of the room, which should be the same length. How long should each diagonal be?