For a 25 inch television screen, the length of the screen's diagonal is 25 inches. If the screen's height is 15 inches, what is the width?

The length (L), width (W), and the diagonal (D) of the television screen make a right triangle with the legs L and W and hypotenuse D. Thus, their measurements are related through Pythagorean Theorem.

L² + W² = D²

Substituting the known values from the given,

(15 in) ² + W² = (25 in) ²

Solving for W in the equation gives, W = 20 in and W = - 20. The second value is an extraneous root. Thus, the width of the television screen is 20 inches.