Marshall wrote:The aspect ratio of a tv screen is the ratio of width to height of the image. A regular TV has an aspect ratio of 4:3. Find the height and width of a 42in. Tv screen to the nearest tenth of an inch. (the measure given is the length of the diagonal across the screen.)
Reply:
Televisions with glass envelope CRTs were measured diagonally. The aspect ratio was always 4:3 (except for special purpose tubes), so measuring the diagonal for tube size was uniform and simple. Modern LCD and plasma type flat-screen TVs are still measured this way. However, with this diagonal measure an aspect ratio is included. The common aspect ratios are 5:4, 4:3, 16:10, 5:3 (sometimes labeled as 15:9), and 16:9.
All of these TVs can have a 42 inch (diagonal) display size, but they will not necessarily display a desirable image. As an extreme example: you could have a TV that has a 42 inch diagonal but is only 4 inches high.
Melody is essentially correct as the formula is a rearrangement of the Pythagorean theorem.
(However, it should be written as
42/5 = Width/4
and
42/5 = Height/3)
The actual formula for this construct is
Height= D * SQR(H 2)/(W 2+H 2)
Width= W/H * D * SQR(H 2)/(W 2+H 2)
Where D is the diagonal measure and
W and H are the aspect ratio expressed as W:H.
It is readily discernible that as ratios increase from 5:4 to 16:9, the angle of the diagonal decreases and, the viewing area (in square units) decreases for any given constant diagonal. In the case of 42 inches it decreases from 847in 2 to 754in 2
BTW I responded to your follow-up question "Need Help Nowwwwww" (Which would have greater continuity if posted here).
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