tan(x) is trigonometric function.
It's domain is R - {(2n+1)pi / 2}. That means it can accepts any real input except the ones which are odd integral multiple of pi/2.
It's range is R. where R means all the real numbers.
The Graph is given below.
It's is a increasing function. That means for all x2 > x1 . F(x2) > F(x2). This can be easily seen from the graph.
