Differential Area of a Circular Hoop

Hello,

OK. So suppose you have a circular hoop of differential thickness dx that has a radius r. I have been told in multiple courses that the differential area of such a hoop is dA=2πr*dx. It is hard for me to see why this is.

Can somebody please explain how this derivation comes about? A proof or explanation would be appreciated.

Re: Differential Area of a Circular Hoop

Re: Differential Area of a Circular Hoop

Fantastic Response. I tended to think of the hoop the second way you mentioned, but couldn't quite get past the squared differential.

Thanks for clearing things up.