Circle Parallel Curves
CircleParallelCurves
The parallel curves of a circle with radius a with offset k are given by the parametric equations
x_p(t) = (a+k)cost
(1)
y_p(t) = (a+k)sint
(2)
and are therefore themselves circles.
See also
Circle, Parallel CurvesExplore with Wolfram|Alpha
WolframAlpha
More things to try:
Cite this as:
Weisstein, Eric W. "Circle Parallel Curves." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/CircleParallelCurves.html