I forgot how to do divergences 3 years ago, this one is very confusing. We used to take them with respect to $x,y,z$ but this one doesn't have them. Help me with this question
Prove that $∇.E = 0$
$E = \frac{IΔz}{4π}jwμ\bigg[1 + \frac{1}{jBr} - \frac{1}{{(Br)}^2}\bigg]\frac{{e}^{-jBr}}{r}\sin(θ) \hat θ + \frac{IΔz}{2π}η\bigg[\frac{1}{r} -\frac{j}{{Br}^2}\bigg]\frac{{e}^{-jBr}}{r}\cos(θ)\hat r$