What are the graphs of y = sin x and y = sec x in the interval from -2pi to 2pi. (send me a screen shot of the graph you get).

The two graphs and the tables to generate them are in the attached pdf file.

y = sin (x) is pretty easy to draw: it is a continuous harmonic function, whose values are well known.

y = sec(x) = 1 / cos(x) is not that simple, because it is not defined on the points where cos(x) is 0  ( -3pi/2, -pi/2, pi/2 and 3pi/2).

In those points you have to calculate the limits when x tends to the value from the left and from the right. That is how you get to + infinity and - infinity.