When I learned solids of revolutions, we divided the solid into infinitely thin "disks" and then summed up their individual volumes to get the volume of the surface.(adsbygoogle = window.adsbygoogle || []).push({});

Now in surface of revolutions, we are divided the solid into infinitely thin fustrums and summing up their individual surface area to get the total surface area of the solid.

My question is: Why can't we just use disk to find the surface of revolution by summing up the surface areas of infinitely thin disks? Why use a fustrum for the surface of revolution but not for the solid of revolution?

BiP

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# Surface of revolutions

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