The locus of points is a sphere inside of the original sphere that has a radius of 3 cm.
Work Step by Step
It is hard to draw this diagram on paper, but it is not too difficult to describe. Recall, a locus is equidistant from the sphere no matter where you are. Therefore, since the book specifies that the locus should be 2 cm from the original sphere, the locus will be a sphere inside of the original sphere with a radius that is 2 cm smaller.