Plot tan, cot, sec and csc on the interval [-2Pi, 2Pi]. (Note that these functions all have vertical asymptotes.) You should know these graphs well. The trigonometeric functions are all periodic, that ...

Given a function f(x), and two points on the curve (a, f(a)) and (b, f(b)) the line joining these two points is called a secant line of f. (Not to be confused with the trigonometric secant (sec) ...