Gramp's shop wrote:
I need to draw an arc for a piece of trim. The end points of the
arc
are 5 feet apart and the depth of the arc at the center point is 2
inches. What is the radius of the circle?

There ought to be an equation for this that would be far superior
to
trial and error, oui?
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"dadiOH" wrote:

Trial and error isn't needed, neither is knowing the radius of the
arc's circle.

Put two nails 5' apart in a piece of ply. Put another nail 2" above
the line formed by the first two. Take a batten, bend it between
the nails and draw the arc.
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Nice try but no cigar.

The end result needed is a cambered beam shape which requires
more than the three points you suggest.

Bingham outlines the method that works in his book.

Have used the method to define the deck cambers which varied from
10' to 16' in length for the boat I built.

BTW, a batten is needed, I used a 3/4" x 3/4" x 1/16" x 96" aluminum
angle which provides a knife edge for fairing out the profile with a
fairing
board.

Lew