Orgueam

i study alone and i'm having difficulties with these issues, please help me! Questions: 1- Determine which type of central grid is from its curves. (X ^ 2) / (a ^ 2) + (y ^ 2) / (b ^ 2) - (z ^ 2) / (c ^ 2) = -1 2- Prove that rotations in R ^ 2 commute. Ra * Rb = Rb * Ra 3- Prove that roca in R ^ 3 do not commute. 4- How to transform cylindrical coordinates into Cartesian coordinates? 5- ρ sin ϕ = 2 A surface in R ^ 3 is given by coordinate (ρ, θ, ϕ), how to translate into Cartesian coordinates and what is this surface?