Search All of the Math Forum:
Views expressed in these public forums are not endorsed by
NCTM or The Math Forum.


Math Forum
»
Discussions
»
sci.math.*
»
sci.math
Notice: We are no longer accepting new posts, but the forums will continue to be readable.
Topic:
Area and volume of solid of revolution
Replies:
14
Last Post:
Nov 28, 2005 11:13 PM



RCA
Posts:
11
Registered:
11/26/05


Re: Area and volume of solid of revolution
Posted:
Nov 27, 2005 1:40 PM


Kyle wrote:
"When finding solids of revolution we first evaluate an integral that calculuates the *area under a curve* and then rotate that quantity.
When finding surfaces of revolution we evaluate an integral that calculates the *length of a curve* and then rotate that quantity. "
Agreed, Kyle. My question is  why does the area under the curve calculation ignore the "arc length" aspect. The arc length is used as the basis for the surface area of revolution while the arc length is approximated to the x component while calculating the volume (or the area under the curve). I dont understand how that is justified.



