If |z - 3i| = 3, (where i = √−1) and argz ∈(0,π2), then cot(arg(z)) - 6z is equal to
0
-i
i
put z cosθ+isinθ, we get |cosθ+isinθ−3i| = 3 ⇒sinθ=16
∴cotθ−6z=i