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Calculating TV width/height, based on diagonal length?

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  • Calculating TV width/height, based on diagonal length?

    Widescreen (16:9) and 4:3 TVs will have a different formula. The manufacturers cheat and tell you the diagonal length, to make the number look bigger, but how do you figure out the width/height with the diagonal length?

    That should get added to the list of conversions.

  • #2
    Re: Calculating TV width/height, based on diagonal length?

    Originally posted by Unregistered
    Widescreen (16:9) and 4:3 TVs will have a different formula. The manufacturers cheat and tell you the diagonal length, to make the number look bigger, but how do you figure out the width/height with the diagonal length?

    That should get added to the list of conversions.
    For a 4:3 tv, the height:width:diagonal are in the ratio 3:4:5. So the height is 3/5 x the diagonal, and width 4/5
    (or 60% and 80%).

    For a 16:9 tv, the ratio is 9:16:sqrt(337). Height is 9*diag/sqrt(337), width is 16*diag/sqrt(337), or about 49% and 87% of diagonal.

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    • #3
      Re: Calculating TV width/height, based on diagonal length?

      nice work thanks

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      • #4
        Re: Calculating TV width/height, based on diagonal length?

        diagonal is 25, height is 15, width?

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        • #5
          Re: Calculating TV width/height, based on diagonal length?

          Originally posted by Unregistered View Post
          diagonal is 25, height is 15, width?
          20" as explained in post 2.

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          • #6
            Re: Calculating TV width/height, based on diagonal length?

            nice job, finally i got it, but honestly the 16:9 not so much, i guess i can find the % given but i want to know how u derive at the % , if u don't mind
            tks

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            • #7
              Re: Calculating TV width/height, based on diagonal length?

              The diagonal squared is equal to the sum of the sides squared. From the 16:9 ratio, I computed the diagonal, and refigured each side to the diagonal as a ratio. If the sides are 9 and 16, the diagonal is sqrt(337) = 18.3576

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              • #8
                Re: Calculating TV width/height, based on diagonal length?

                This is pythagorean theorem: The sum of the sides squared is equal to the diagonal squared

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                • #9
                  Re: Calculating TV width/height, based on diagonal length?

                  You take both sides 3 and 4 and use arctan to get the angles that are not 90deg. Repeat the process with the 16 and 9. Then use the law of sines to get that the W*0.85=SD. Where W is the widescreen diagonal and SD is the 3:4 diagonal measurement.

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                  • #10
                    Re: Calculating TV width/height, based on diagonal length?

                    My teacher gave me a worksheet that says ''Going to the mtric lengths''.And im on number 2 it says what is the height of the tv.i have no idea and it doesnt tell us what kind of tv it is.im really confused on it.who can help me on this!!!!!

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                    • #11
                      Re: Calculating TV width/height, based on diagonal length?

                      Originally posted by Ez breezy View Post
                      My teacher gave me a worksheet that says ''Going to the mtric lengths''.And im on number 2 it says what is the height of the tv.i have no idea and it doesnt tell us what kind of tv it is.im really confused on it.who can help me on this!!!!!
                      You'll need to give us more information. Type out the complete question.

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                      • #12
                        Re: Calculating TV width/height, based on diagonal length?

                        A television screen measures approx. 18.5 in. high and just over 26 in. wide.
                        How should the size of this television be advertised?

                        My question is how do I figure this problem out? I have tried to add or divide but it does not make sense to me! Please help

                        Comment


                        • #13
                          Re: Calculating TV width/height, based on diagonal length?

                          Originally posted by Unregistered View Post
                          A television screen measures approx. 18.5 in. high and just over 26 in. wide.
                          How should the size of this television be advertised?

                          My question is how do I figure this problem out? I have tried to add or divide but it does not make sense to me! Please help
                          Hint, hint: A guy named Pythagoras has a theorem about this very subject, even though TVs didn't exist in his time, only triangles.

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                          • #14
                            Re: Calculating TV width/height, based on diagonal length?

                            Let d = diagonal, l = length, w = width. Let AR = l/w. AR = 16/9 = 1.78 for a wide screen.
                            We are given d. We want to compute l and w. Below ** means exponential, * means times, and SQRT means square root.

                            Solution:
                            l = AR * w
                            d**2 = l**2 + w**2 (Pythagorus). Substituting

                            d**2 = (AR**2) * (w**2) + w**2 = (AR**2 + 1) * w**2. So,
                            w**2 = d**2/(AR**2 + 1). So the general formula is

                            w = = d/(SQRT(AR**2 + 1)
                            l = AR * w.

                            For the wide screen AR = 1.78. So
                            w =.49 * d
                            l =.87 * d

                            For standard screen, do the math for the appropriate AR.

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                            • #15
                              Re: Calculating horizontal linearity width in %?

                              How i can measure horizontal width linearity % in a color television by using chroma pattern generator?

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