Question

How do you know if a graph you are looking at shows a periodic function? How do you determine the period of the graph?

Answer 1

Answer:

A function f(x) is said to be periodic, if there exists a positive real number T such that f(x+T) = f(x).

You can also just say: A periodic function is one that repeats itself in regular intervals.

Step-by-step explanation:

The smallest value of T is called the period of the function.

Note: If the value of T is independent of x then f(x) is periodic, and if T is dependent, then f(x) is non-periodic.

For example, here's the graph of sin x.  [REFER TO PICTURE BELOW]

Sin x is a periodic function with period  2π  because  sin(x+2π)=sinx  

Other examples of periodic functions are all trigonometric ratios, fractional x (Denoted by {x} which has period 1) and others.

In order to determine the period of the determined graph however, just know that the period of the sine curve is the length of one cycle of the curve. The natural period of the sine curve is 2π. So, a coefficient of b=1 is equivalent to a period of 2π. To get the period of the sine curve for any coefficient b, just divide 2π by the coefficient b to get the new period of the curve.

Hopefully this helped a bit.