I am in little bit of a hurry right now, but I think the basic principle is as follows. You would have to extrapolate the figure to where the two straight lines intersect. Then you have two pies, a large one, from which you have to deduct the small one (the cut-off tip). For each of the pies, the formula would be pi() * r^2 * (degrees / 360). (Note: pi() * r^2 is the formula of the circle, so you are getting a fraction of a circle here.)

HTH,

Hilmar.

>Picture a narrow cone with the top lopped-off. More like a tower, but the bottom circumference is larger than the top. Ok, a lighthouse. Now, cut it down the side and lay it out flat. Basically it would be something like a rhombus with a concave top and a convex bottom. How could I calculate/create that design knowing the dimensions I want my final shape to be? Something like this:
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>                    .      .
>                   . ` .. ` .
>                  .          .
>                 .            .
>                .              .
>               .                .
>              .                  .
>               .                .
>                 .           .
>                     `   `
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