Hi machinster, talking of a Haas machine; input the correct diameter of the part to be machined in the Setting #34, and then all you have to program is something like this:
G01 X2.500 Y0 A131.523 F5.1
Knowing the diameter of the part, the control will interpolate both axis to reach the end of the move at the specified rate.
Here is a partial Haas post that I used for years.
name Haas 4 axis VF2 (Metric) ( BY Mario Lovato 15/04/1997 )
% 00
/ 00
O >4
N >4
A ->4.>3 Limit -8000 8000
I ->4.>3
J ->4.>3
K ->4.>3
ModalLetters X Y Z F A # List of letters that are modal
ModalGs 0 1 2 3 73 74 76 80 81 82 83 84 85 # List of g codes that are modal