The television set has a rectangular shape. The diagonal of this rectangle along with its width and length together form a right angular triangle. This means that we can apply the Pythagorean theorem which states that: (diagonal)^2 = (length)^2 + (width)^2
Let the width be w. We know that the length is 0.75 times the width, this means that: length = 0.75 w
Substitute in the above equation: (20)^2 = (0.75w)^2 + (w)^2 400 = 0.5625 w^2 + w^2 400 = 1.5625 w^2 w^2 = 256 w = 16
