[Groff] Drawing filled circle segments

[Clarke Echols]

I need to use drawing requests (\D'...') directly (without
using PIC) to make pie-chart segments that can be filled with
color.

I have no problem getting filled boxes and polygons, but I
have not discovered how to draw two lines with an included
angle, then connect the two outside ends with an arc whose
radius is centered at the vertex of the two lines.

Any suggestions?  I must be missing something very obvious...

Thanks,

Clarke