I need to find the length of a Chord of a circle given that I have the Arc length and Arc Height (that's all), no radius or anything else.

I suspect that I will need a radius to find this. Or am I missing a point here?

The below spreadsheet I found on the web proports to be able to do this but the answer is not correct. The edges of my material does not match up when I calculate the Chord length given that I've entered the Arc Length and the Arc Height.

Does anyone know how to do this?

Thanks

http://mathforum.org/dr.math/gifs/ChordMath.xls