A backlight assembly includes a light guide plate having at least five sides. There is a first side. A second side is parallel to and equal in length to the first side. A third side is perpendicular to the first and second sides. A fourth side is parallel to and shorter in length than the third side. There is at least one oblique side connecting the fourth side to the first or second side. The backlight assembly additionally includes a light source unit disposed the fourth side and the oblique side of the light guide plate.