Fiona’s TV screen is 20 inches long. The diagonal measures 25 inches.
How long is the width of Fiona's TV?
Using the Pythagorean theorem:
Width^2 + Length^2 = Diagonal^2
Width^2 + 20^2 = 25^2
Width^2 + 400 = 625
Width^2 = 225
Width = √225
Width = 15 inches
Therefore, the width of Fiona's TV is 15 inches.