**cos()** function is a built-in function in R that calculates the cosine of a single number or a vector of numbers. This guide shows how to use the **cos()** function in R.

## Syntax

`cos(x)`

## Argument

**x**= It is the numeric vector you want to calculate the cosine of.

Here are some examples of the cos() function in R:

## Example 1: Calculate the cosine of a number

```
#calculating the cosine value of a number
cos(0)
#calculating the cosine value of a number stored in a variable
x = 5
cos(x)
```

#### Output

```
[1] 1
[1] 0.2836622
```

## Example 2: Calculate the cosine of a vector

```
#calculating the cosine value of a vector
x = (c(0,1, 2))
cos(x)
```

#### Output

`[1] 1.0000000 0.5403023 -0.4161468`