Find the boundary of the functions domain determine if the

Question

For the function f(x,y) = tan^-1(y/x),

a) Find the function's domain,

b) Find the function's range,

c) Describe the function's level curves,

d) Find the boundary of the function's domain,

e) Determine if the domain is an open region, a closed region or neither, and

f) Decide if the domain is bounded or unbounded. Explaination and solution would be greatly appreciated!