Every CAD package out there will draw an arc and a circle. No problem to draw it to size by entering the radius or diameter. It will be the right number of drawing units and if your output and drawing units match, you have a "to scale" drawing.
If you are drawing in inches and your CAM outputs MM then you will be disappointed - especially if your machine runs in inches!
CAD packages are all different but they operate very similarly. Some are easy to learn, others can take years to learn.
Scott
Consistency is a good thing....unless you're consistently an idiot.