Question 156780
The measurement of a TV is usually done diagonally.  Therefore, the width, length, and the diagonal forms a "right triangle".  You can now apply Pythagorean theorem to solve your problem.
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A 30 in tv set also has a width of 24 inches.  What is its height?  
30^2 = 24^2 + h^2
30^2 = 24^2 + h^2
900 = 576 + h^2
324 = h^2
18 inches = h (height of TV)