Hi, I'm not sure of the answer to this question (or even if belongs in this forum, apologies):

Let ϕ: C → C be the rotation of angle θ around the point ∈ C.

Express ϕ(z ) in terms of z , and e^iθ.

I know that z = (r, θ) in polar coordinates means z=re^iθ , but I don't know how to express ϕ(z). My best guess is ϕ(z) = e^iθ but I don't really understand how to visualize this rotation or where z is.

Thanks so much for any help.