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LCD Mathematicians.

Discussion in 'LCD & LED LCD TVs Forum' started by nal, Nov 27, 2004.

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  1. nal

    nal
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    A nice question for all you mathematicians out there.

    Is there a formula for working out "widescreen" dimensions from the diagonal, the reason I ask is I want to replace the 4:3 tv in the bedroom for a lcd widescreen and would like to keep the same height .... I don't want to look an idiot going round the stores with a measuring tape.

    eg. 17" widescreen works out about 14.75" x 9" (w x h)

    tia,

    nal.
     
  2. flatpanel

    flatpanel
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    Are you sitting comfortably ? :boring:

    The answer depends upon the number of pixels.

    If the screen is true 16:9 i.e. 1366 x 768 then you have two simultaneous equations.

    The first is the ratio of the two sides to one another

    w = 1366/768 x h (where the width is "w" the height "h" and the diagonal "d")

    The second using Pythagoras is

    h^2 x w^2 = d^2 (ie h squared x w squared etc)

    So substituting for w in the second equation you end up with

    h = d/2.0405

    So if you are looking at a 26 inch screen its vertical height is 12.74 inches.

    To be entirely accurate you should use the metric size of the screen rather than the imperial as the inches are usually an approximation.

    Michael
     
  3. nal

    nal
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    Thankyou for that Michael, I was estimating somewhere around a 22/23" to replace my 20" 4:3. As you rightly point out it depends on the aspect ratio of the screen which the 17" I took the measurements from is not 16:9.

    Allan.
     
  4. flatpanel

    flatpanel
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    nal

    I switched from an 18 inch 4:3 to a 26 inch LCD and the overall impression is that it is much bigger even thought the vertical height is only slightly greater.

    Part of the reason is that with the 4:3 I was watching 16:9 programmes with black strips at the top and bottom so the true comparison is with the height of the image not the height of the screen (if that makes any sense).

    Michael
     

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