40 mm
가
32 mm
b
What is the perimeter?

Any two circles are similar, but you can always scale one of them to match the other. if you have two circles, you can re-scale one circle in order to have the same radius as the other circle, and then you could translate the center of one circle to the center of the other circle.
hope this .
so, a would we correct step.
then you could translate circle a using the rule (x-3, y-6) to translate the center of circle a to center of circle b.