The domain is the set of valid values for x that give real values for y. (not complex or imaginary)
Square roots have to be positive.
tan(x) - tan^2(x) >0
gives:
tan(x)>tan^2(x)
divide by tan(x) [eliminating where tan(x) = 0; i.e. x can't be any odd multiple of pi/2]
1> tan(x)
Looking at the unit circle, tan(x) is greater than or equal to 1 from pi/4 to pi/2, and from 5 pi/4 to 3 pi/2.
3 pi/2 < x < 0, or 0<= x < pi/4, or pi/2 < x < 5 pi/4.
since tan(x) is cyclical, you can add any multiple of 2 pi to the inequalities as well.
3 Pi/2 + 2 pi n < x < 0, or 0 <= x <= pi/4 + 2 pi n, or pi/2 + 2 pi n < x < 5 pi/4 + 2 pi n, where n is any integer.
