1. The problem statement, all variables and given/known data Identify the following surfaces: i) r.u=L ii) r.u=mlrl for -1[itex]\leq[/itex]m[itex]\leq[/itex]1 where k, L, m are fixed scalars and u is a fixed unit vector. 2. Relevant equations 3. The attempt at a solution The first one is in the same form as the equation of a plane, but u is not necessarily the normal, so I'm confused. For the second one, I have no idea.