Math question: actual size based on resoution and monitor size

[ShakeZula06]

I'm looking into buying a monitor that can support more tables with less overlap. The monitor I'm looking at right now has a 21" screen with max resolution of 2048x1538. I was wondering how big the actual size of the tables are in inches, assuming a 800x600 resoultion table. here's what I got.

21" is the distance from one corner to it's opposite, and if that line cuts the screen in two it would be the hypotenuse of two traingles that would remain. So using c^2=a^2+b^2, and making c^2= 441 (21^2=441) we then have

441=a^2+b^2. Being that 2048/1538=1.33(rounded to two decimals) that puts us at a 1.33x1 scale. Does that mean a=1.33b (or b=1.33a)?

If that is correct, we can assume (a^2)+(1.33a^2)=441, and

I didn't know whether this was the same as 2.33a^2=441 (which would make this much easier, just divide 441 by 2.33 to get a^2 I think) but after plugging in 2 for a I got 6.66 for the first equation and 5.43 for the second number, so the 2nd equation cannot be the same as the first right?

Finding out this gives us the height and width of the monitor. From there we can find out resoultion per inch for both the height and the width, and from there find out how big a 800x600 table would be.

So assuming the first equation has the answer, how do we solve this? If it's not right, how do you solve this? If I completely wrong, how do you solve it? It's 4 in the morning and I'm tired and this was racking my brain while I was laying in bed so I decided to post it.

Thanks a lot for any help,
Ben

[BruceZ]

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If that is correct, we can assume (a^2)+(1.33a^2)=441

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No, it's a^2 + (1.33a)^2 =~ 441.

a =~ 12.61 inches for 1538 pixels

800 pixels =~ 12.61*(800/1538) =~ 6.56 inches
600 pixels =~ 12.61*(600/1538) =~ 4.92 inches

[BruceZ]

One issue with this calculation is that the actual viewable size of your monitor probably measures less than 21" by an inch or so. Most 17" monitors have viewable image sizes of 15.7". My 19" monitor has a diagonal of 17.75".

[Jeremy517]

[ QUOTE ]
One issue with this calculation is that the actual viewable size of your monitor probably measures less than 21" by an inch or so. Most 17" monitors have viewable image sizes of 15.7". My 19" monitor has a diagonal of 17.75".

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Depends. CRTs are measured from corner of the monitor to corner of the monitor, while LCDs are measured from the corner of the screen to corner of the screen.

[ShakeZula06]

tyvm sir

[BruceZ]

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CRTs are measured from corner of the monitor to corner of the monitor

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Not the outermost corners of the box, as my 19" CRT monitor measures 23.75" that way. I've read that the screen is measured on the CRTs as well, but they include a portion of the screen which is covered by the frame. The law requires that the manufacturer also disclose the actual viewable image size.

[KeysrSoze]

My so-called 21" monitor (Viewsonic P225f) is 19.5" viewable diagonal, 15.75" horizontal and 11.75" vertical. 70hz refresh rate at 2048x1536, which may or may not cause headaches depending on the viewer.

[Siegmund]

The equation is somewhat easier if you recall your old friend the 3:4:5 right triangle from junior high geometry... 20" diagonal = 12x16 sides, similarly for any other size. From there ought to be an easy pixels-per-inch conversion. There was a time they advertised the 'dot pitch' of monitors, but that seems to not be fashionable anymore...