How do you work out the Arg of a complex number?

A complex number z = x+iy or (x, y) can be also represented as (r, θ) in polar coordinate, where r = √(x2+ y2) and θ = tan-1(y/x). Here θ is known asArg(z). And the values of θ in

]-π, π] is known as principal value of the argument and is represented as arg(z). It is evident that Arg(z) = arg(z) + 2nπ.