The equation is tan^2(X) = 2tan(X) where X is an element of [0, 360)

As you can see, the interval is half-open. My question is, will the solution look like this:

X = arctan A = tan^-1(A) + 180n because inverse tangents come in pairs a half revolution apart

or this:

X = arctan A = tan^-1(A) + 90n because the system is only half open?

(X=Theta but I don't know how to make the symbol)