Let S = {(ξ; η; ζ ) ∈ Σ : ζ ≥ ζ₀g}, where 0 < ζ₀ < 1 and let T be the corresponding
set in C. Show that T is the exterior of a circle centered at 0.
Im really confused by this problem, can anyone please help me.
I suppose the " " appearing in is a typo. Using the well known equations of the Stereographic Projection we get and . That is, is the the complement in of an open disk centered at and radius (the complement, not the topological exterior).