



The **`Cos`** function in the Go programming language is used to find the cosine value of a number. 

To use this function, you must import the `math` package in your file and access the `Cos` function within it using the `.` notation (`math.Cos`). Here, `Cos` is the actual function, while `math` is the Go package that stores the definition of this function.

# Function definition

The definition of the `Cos` function inside the `math` package is:


# Parameters
The `Cos` function takes a single argument of type `float64`. This argument represents the angle whose cosine value you want to find.




# Return value

The `Cos` function returns a single value of type `float64`. This value represents the cosine value of the argument. The possible range of all return values is between -1 and 1 (both inclusive).

>  ﻿An exception to the above statements is when you pass something that is +infinity, - infinity, or `NAN` as an argument. In these cases, the `Cos` function returns `NAN.`


# Examples



Following is a simple example where we find out the cosine value of 25:

package main

import (
  "fmt"
  "math"
)

func main() {
	x := 25.0
	y := math.Cos(x)
	fmt.Print(y)
}

The following example shows how passing an infinite number as an argument makes the `Cos` function return `NAN`:

package main

import (
  "fmt"
  "math"
)

func main() {
	y := math.Cos(math.Inf(1))
	fmt.Print(y)
}

What is the Cos function in Golang?

The Cos function in Go computes the cosine of a float64 angle, returning values between -1 and 1. NAN is returned for infinite or NAN inputs.