Cutting an arc help G2/G3?

I have to cut a small workpiece with a curve. The workpiece will be
2.5 inches long, 1" wide and 1/2" thick. The long end of the
rectangle needs to be cut in an arc to match a 12" circle, the
shorter inside arc to match an 11" circle. Hard to describe, think
of a 2.5" long piece cut out of a 12" ring that is 1" wide.

Assuming I start with a workpiece that is a rectange 2.5" long by 1"
wide, how would I program the arc cut? I can see programming a
circle and letting the machine make a 12" revolution, but that would
be really slow. I'm not sure how to program just the part of the arc
that I need.

Thanks,

George



(FYI: My controller software (Microkinetics Millmaster Pro)
recognizes I and J parameters but not the R parameter with G2/G3)