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#### thegratingone

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Here's a basic question that's probably been asked and answered millions of times:

If you have a 16:9 T.V., and are showing 4:3 with the sidebars, what size 4:3 is equivalent to the 16:9? That is, if I have a 38" 16x9 T.V., what equivalent size 4:3 image will I be showing?

I could probably work through the geometry (though it has been awhile!), but conventions vary, and the true answer isn't always the math answer.

Thanks.

#### Delvo

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According to the Pythagorean Theorem, the diagonal of a 4:3 rectangle is 5, and the diagonal of a 16:9 rectangle is the square root of 337. Thus, it's easy to find the ratios of either screen's diagonal to either its height or its width. You're looking for the diagonal of one screen based on the diagonal of another when both are the same height. So you'd multiply the widescreen's diagonal with the widescreen hieight-diagonal ratio (9 over the square root of 337) and the standard screen diagonal-height ratio (5/3), which combine to about 0.817102066. Multiply this by 38", and you get a 31" 4:3 picture. Multiple it by 34", and you get a 27-and-three-fourths-inch 4:3 picture. Multiply it by 65", and you get a 53" 4:3 picture...

#### Allan Jayne

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If you are seeing a 4:3 picture (with side bars) on your 16:9 TV, the picture is about the same size as on a 4:3 TV with a 22% smaller diagonal size. Call it 20%

If you are seeing a 16:9 or greater (letterboxed) picture on your 4:3 TV, the picture is about the same size as on a 16:9 TV with an 8% smaller diagonal size. Call it 10%.

Video hints:
http://members.aol.com/ajaynejr/video.htm

#### thegratingone

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Thanks to both of you (and to Pythagoras - I'm way too Riemann oriented to have figured this out ).

#### hob

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Too bad you don't have x, y, scaling or zoom cabilities, My Toshiba SD-4800 has zooming with a disapeering icon. Take small letter box up to what ever size you want, then press down arrow and center; your icon is gone, but your ratio is still there to view.

#### Ken Garrison

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Maybe screen sizes should by measured by height, and not diagnal.

#### Joe Murphy Jr

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