Recall that a linear function is a function whose graph is a straight line, that is, a polynomial of degree one or zero.
Now, notice that the given function is a polynomial function of degree 1, also notice that is in slope-intercept form:

where m is the slope and (0,b) is the y-intercept.
Therefore, the slope of the given linear function is π.
Answer: The given function is a linear function, and its slope is π.