The base of a solid is the circle x^2 + y^2 = 9. Cross sections of the solid perpendicular to the x-axis are squares. What is the volume, in cubic units, of the solid?

Answer 1

each square of thickness dx has side 2y, so its area is 4y^2.

Adding up all the thin squares, and using symmetry,

v = 2∫[0,3] 4(9-x^2) dx

Answer 2

Awsome...thnx