"quick question.
look at the inner and outer rims of the circular plate shown below.
what are the inner and outer rims called? "

Based on the given figure of a plate above, the inner and the outer rims are called CONCENTRIC CIRCLES. By definition, concentric circles are circles having the same or common centers. And in the figure, both the outer and the inner rims have a common center. In addition, the part between two concentric circles of different radii is called an annulus. Hope this is the answer that you are looking for.

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