The parallel curves of a circle with radius with offset are given by the parametric equations
(1)
 
(2)

and are therefore themselves circles.
The parallel curves of a circle with radius with offset are given by the parametric equations
(1)
 
(2)

and are therefore themselves circles.
Weisstein, Eric W. "Circle Parallel Curves." From MathWorldA Wolfram Web Resource. https://mathworld.wolfram.com/CircleParallelCurves.html