Here, (s) is typically the length of the cross‑section at a given (x) or (y), found as the difference between two bounding curves. Problem: The base of a solid is the region bounded by (y = \sqrtx), (y = 0), and (x = 4). Cross‑sections perpendicular to the x‑axis are squares whose bases lie in the base region. Find the volume.
[ V = \int_c^d A(y) , dy ]
For cross sections :