Question

Show that the period of$f\left(\theta \right)=\cos \theta$is$2\pi$.

Short answer

From the following graph of cosine function $f\left(\theta \right)=\cos \theta$it is clear that the period of cosine function is $2\pi$.

Step-by-step solution

Step 1. Given Information

We have to prove that the period of cosine function is $2\pi$.

We will draw the graph of this function. After that from the graph we will examine the period of the function.

Step 2. To find period of cosine function 

The given function is :-

$f\left(\theta \right)=\cos \theta$.

By using graphing utilities, we have the following graph of this function :-

We can see that curve of the graph repeated itself.

We know that the period of a function is where from the graph of function repeated itself.

We can see that after $2\pi$, repeating itself as it is from $0$to $2\pi$.

Similarly the graph is from $-2\pi$to $0$is same as $0$to $2\pi$.

So we can conclude that the period of the given function is $2\pi$.