Geometry question

I want to make a table top with a slight arc along the edge. I know the length of the side (the chord) and I know the height of the arc above the chord. Anyone know the formula to calculate the radius of the circle?
TIA Ron
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Ron Hock
HOCK TOOLS -- http://www.hocktools.com
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the
I believe this is what you're looking for (bottom) http://www.delorie.com/wood/chord-radius.html
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Man, this web thing takes the joy out of trying to remember old HS geometry!
Anyways, came up with the same thing, R = (x^2 + y^2)/(2*y), where y is half the length of the chord and x is the height above the chord...
i.
Norm Abrams wrote:

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above
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Thanks everyone. You saved me a lot of research time and I never even thought of using AutoCad...
Ron
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Ron Hock
HOCK TOOLS -- http://www.hocktools.com
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http://mathforum.org/library/drmath/view/55037.html
link to XL spreadsheet (watch out for line wrap)
http://216.239.51.104/search?q che:6GIlO2OZGFMJ:www.ukuleles.com/spreadsheets/ArcCalcs.XLS+chord+radius+length+arc&hl=en&ie=UTF-8
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wrote:

Let l be the length of the chord h be the chord-arc height
r the radius and d the distance from the centre to the chord
Then r = ( (l^2 / 4) + h^2 ) / 2h
d = ( (l^2 / 4) - h^2 ) / 2h
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That's easy. AutoCAD.
UA100
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Yes, the $3400 calculator. You can do better for a lot less money.

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He would cut a ten foot radius I would assume.

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He would cut a ten foot radius I would assume.
[top-posting fixed]
I was more thinking along the lines of how, but Bruce's suggestion is a good one.
todd
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I had to cut a twenty four foot radius for a template one time. I did it with a router circle jig.

good
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In rec.woodworking

You could make a string compass and draw that part of the arc on a sheet of cardboard. Go out on the driveway if you need room. Done.
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The optimized formula is: chord squared, divided by 8 times the height, then add half the height.
example: chord: 10 height: 2
radius = ((10*10)/(8*2)) + 2/2 radius = (100 / 16) + 1 radius = 6.25 + 1 radius = 7.25     
The derivation of the above gets messy.
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