# Acosh()

Published Sep 27, 2023
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The `Acosh()` function returns the inverse hyperbolic cosine of a number.

## Syntax

``````result := math.Acosh(number)
``````

The `Acosh()` function takes one parameter, `number`, of type `float64`. And the method also returns a `float64`. This value represents the inverse hyperbolic cosine, or arccosh, of `number`. It’s important to note that the returned value is in radians. If the value of `number` is:

• Not defined (`undefined`), then it returns `NaN` (Not a Number)
• Less than `1`, including negative infinity (`-Inf`) or equivalent, then it returns `NaN`
• Greater than or equal to `1`, including positive infinity (`+Inf`) or equivalent, then it returns `+Inf`

Note: The `math` library must be imported first to use this function.

## Example

The following example first calculates the inverse hyperbolic cosine of `num` and then prints out the result to the console:

```package main
import (  "fmt"  "math")
func main() {  num := 16.0
inverseHyperbolicCosine := math.Acosh(num)  fmt.Printf("The inverse hyperbolic cosine of %f is %f\n", num, inverseHyperbolicCosine)}
```

The output will be:

```The inverse hyperbolic cosine of 16.000000 is 3.464758
```

## Codebyte Example

The following example is runnable and uses the `Acosh()` function with two values: positive infinity and `0.5`:

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