# Ruby – Find Inverse Hyperbolic Cosine – acosh() Method with Examples

`acosh()` method can be used to find the inverse hyperbolic cosine of the any given complex number in Ruby. `acosh()` method exists in `CMath` library of Ruby.

## `acosh()` Method in Ruby

`acosh()` method exists in Standard CMath Library of Ruby. The purpose of this method is to provide perfect inverse hyperbolic cosine for the given complex number.

## Syntax of the `acosh()` Method in Ruby

Syntax of `acosh()` method is:

```cmath.acosh(x)
```

## Parameter of `acosh()` Method in Ruby

 Parameter Description `x` Any valid complex number. This parameter is required.

Note: If the `x` parameter is not a complex number,`acosh()` method will return an `error`.

## Return Value of `acosh()`

`acosh()` method will return the inverse hyperbolic cosine of the given numeric complex number.

## Ruby – Get the `acosh()` of the Given Numbers Example 1

``` # import CMath library
require 'cmath'
x = CMath.acosh(1 + 1i)
puts x
```

Output

` 1.0612750619050357+0.9045568943023813i`

## Ruby – Get the `acosh()` of the Given Numbers Example 2

``` # import CMath library
require 'cmath'
x = CMath.acosh(-1 + 1i)
puts x
```

Output

`-1.0612750619050355-2.2370357592874117i`

## Ruby – Get the `acosh()` of the Given Numbers Example 3

``` # import CMath library
require 'cmath'
x = CMath.acosh(0 + 0i)
puts x
```

Output

` 0.0+1.5707963267948966i`

## Ruby – Handle Negative Values in `acosh()` Method Example 1

```# import CMath library
`require 'cmath'` x = CMath.acosh(-5 - 5i) puts x```

Output

` -2.649196177806475+2.3511949067802878i`

## Ruby – Handle Negative Values in `acosh()` Method Example 2

``` # import CMath library
require 'cmath'
x = CMath.acosh(-5)
puts x
```

Output

` -2.2924316695611733+3.141592653589793i`

## Ruby – Getting the `acosh()` of a Particular Number

``` # import CMath library
require 'cmath'
x = CMath.acosh(9)
puts x
```

Output

` 2.8872709503576206`