Hi,

I have this problem:

the surfaces r=2 and 4, $\displaystyle \theta=$30 degrees and 50 degrees, $\displaystyle \phi=$20 degrees and 60 degrees identify a closed surface.

1- find the enclosed volume.

2- Find the total area of the enclosedsurface. ( I think it is a typo from the teacher. It isvolumenot surface)

The first question is straigth forward

For the secon question I have some issues.

Do I need to take take each element of surface (in spherical coordinates)

,dS1=$\displaystyle r^2$$\displaystyle \sin\theta$$\displaystyle d\theta$$\displaystyle d\phi$

dS2=$\displaystyle r$$\displaystyle dr$$\displaystyle d\phi$

dS3=$\displaystyle \sin\theta$$\displaystyle r$$\displaystyle dr$$\displaystyle d\phi$

then integrate the according the limits and the total are should be

S= S1+S2+S3

Is my reasonnig correct?

Thank you

B