In the unit Applications of the Integral, we rotate the graph around the s or y axis (revolution)..

Now, when do I know when to use 2 pi r or pi r^2?

This is getting pretty confusing..

Question

In the unit Applications of the Integral, we rotate the graph around the s or y axis (revolution)..

Now, when do I know when to use 2 pi r or pi r^2?

This is getting pretty confusing..

3mar · Answer

Could I help you?

user123 · Answer

yes please

3mar · Answer

Of course.
With my pleasure!


I think you are asking about the applications of integration of finding lengths and areas!
Am I right?

user123 · Answer

Yes, finding volumes and areas. 

Also there is this thing where you put "(x-0)" as the radius, and I do not understand why they do that, either.

user123 · Answer

Thank you for trying to help, by the way. :)

3mar · Answer

Don't mention it, dear!
I am here for your help.

3mar · Answer

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