# Surface area of a revolution, why is this wrong?

• I
Why is this way of thinking wrong?. can't I assume that when Δx tends to zero is a sufficient approximation of what I want to get? It confuses me with the basic idea of integrating a function to get the area beneath a curve of a function (which isn't also as perfect) .

PD: I put Δx tends to infinity in the image but I think the right way I was thinking is to zero.

Thank you. ç

(English is not my first language).

#### Attachments

• DSC_0491.JPG
16.1 KB · Views: 421

jedishrfu
Mentor