Transform vectors from cartesian to cylindrical coordinates?

kek

1. The problem statement, all variables and given/known data

How do I transform a vector from cartesian to cylindrical coordinates?

v=(x,y,z) = (λx,λy,0) where lambda is a constant.

Thanks guys,

2. Relevant equations



3. The attempt at a solution

I tried v = (r,θ,z) = (λrCosθ, λrSinθ, 0) but my teacher said it wasn't right.