In this tutorial, learn how to use the ACOS function to **find the inverse of cosine** of a number or cos inverse in excel. It returns an angle which you have to convert in degree using the below methods.

## What is the ACOS Function in Excel

An ACOS function is the trigonometric function under the **category Math/Trig** of Excel. It is a built-in function of MS Excel you can use when you want to calculate the inverse of cosine.

You can find the inverse cosine angle with `ACOS()`

using the methods given below. We can say that its result is cos inverse in excel

## Syntax of ACOS Function

The syntax of the ACOS function is given below which contains a single argument.

1 |
ACOS(number) |

## Argument Passing to ACOS Function

There is only a single argument or parameter of the function to pass. See the description of the argument is given below.

Parameter Name | Description |
---|---|

number |
The number is the value between -1 to 1 that you have to pass as an argument to get cos inverse in excel. |

Now, let’s check the various examples to find the inverse cosine of a number.

## Find Inverse Cosine of a Number to Get Cos Inverse in Excel

There are many examples given below to find the inverse cosine of value from -1 to 1.

**Example 1**

1 |
=ACOS(0.5) |

Output

**Example 2**

The -1 number if pass as the argument will give the value of PI() as the output. The value of the PI is 3.141593 as given in the below example.

1 |
=ACOS(-1) |

Output

**Example 3**

1 |
=ACOS(1) |

Output

So, you have calculated the inverse cosine of any number between -1 to 1. The above outputs to get cos inverse in excel is in radian and not in degree. To convert them to a degree, you have to follow the method given in the next section. So, **read further to find** the required method.

## How to Convert Radian to Degree

To convert radian to a degree, you have to multiply the inverse cosine value with the value `180/PI()`

. Check the below example to use and convert your output to a degree.

**Example 1**

1 |
=ACOS(0.5)*180/PI() |

Output

**Example 2**

1 |
=ACOS(-1)*180/PI() |

Output

**Example 3**

1 |
=ACOS(1)*180/PI() |

Output

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I hope you like this tutorial on how to use the ACOS function in Excel to get cos inverse in excel.

**Reference**

MS Office Support