I am working through this problem and part A is easy enough to show but part b and c have me wondering if I am on the right path.

For part b–

I get the point p = r’ sin(theta) – r

Then dV = k*sigma * 2 * pi * r’ ^2 cos(theta) d(theta)/ (r’^2 + r^2 – 2 r r’ sin(theta))^(1/2)

For integration, apply substitution method:

(r’^2 + r^2 – 2 r r’ sin(theta)) = x

=> -2 r r’ cos(theta) d(theta) = dx

When theta = -pi/2, …

Electric potential due to charged spherical shell is estimated.