Inner Radius: Referring to k(y), it represents half the distance between g(y) and k(y) in terms of distance from the axis of rotation.
Outer Function: In this case, g(y) acts as an outer function since it surrounds and contains k(y). It determines how far from the axis our washers will be formed.
Concentric Circles: A term used to describe circles that share a common center but have different radii, similar to how g(x) and k(x) form concentric circles when rotated around an axis.