1. The problem statement, all variables and given/known data I'm having a problem with solving the domain of |x^2+y^2|<=|z^2|. 2. Relevant equations 3. The attempt at a solution From what I got this should be separated into two expressions: x^2+y^2<=z^2, and x^2+y^2>=-z^2. The later doesn't have a real solution because of the negative root. The first one should then be z>=+-sqrt(x^2+y^2). I can understand that z>=+sqrt(x^2+y^2) is above the positive cone(inside), but where is z>=-sqrt(x^2+y^2) supposed to be? I'm thinking above the negative cone(outside), but I'm not sure.