1. Section 14.5
The Area Problem;
The Integral

42. How is it calculated - 2
Just like the area under a continuous curve can be approximated by a series of narrow rectangles, the volume of a solid of revolution can be approximated by a series of thin circular discs:
we could improve our accuracy by using a larger and larger number of circular discs,
making them thinner and thinner

43. Volume of Revolution Formula
The volume of revolution about the x-axis
between x=a and x=b is:
This formula you do need to know
Think of is as the um of lots of circles
… where area of circle = r2