What does a period mean in maths?

Answer 1

A function f(x) of the variable x, has a period k where k is some constant, if

f(x+ k) = f(x) for every x.

It is easy to show that f(x + nk) = f(x) for any integer n.

What the above two formulae imply is that the values of the function repeat after an interval (or period) of k. The trigonometric functions are some of the better known periodic functions.