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## Homework Statement

Calculate the integral

[tex] \int_{S} (\frac{A}{r^2}\hat{r} + B\hat{z}) \cdot d\vec{S} [/tex]

Where S is the sphere with r = a.

**2. The attempt at a solution**

I have no clue how to solve this problem. I have thought of introducing spherical coordinates and somehow finding a connection but I don't think that works.

I tried breaking out [tex] d\vec{S} = \frac{\partial \vec{r}}{\partial u} \cdot \frac{\partial \vec{r}}{\partial v } dudv [/tex]

using the formula above but not sure on how the dot product works. What confuses me with the integrand with the z and r. The answer is [tex] 4πA [/tex].