If there are multiple circles and they all have the exact same diameter, should it be expressed as "the diameter of the circles" or "the diameters of the circles"?
First I thought it would be "diameters" because each of these circles individually has one diameter even if the lengths are the same, but then I thought if the diameters are all the same, they could probably be referred to as "the diameter". And I'm thinking, if the circles each have a different diameter, it should be "the diameters of the circles". Is this correct? I want to know the correct way of use.