In this tutorial, learn how to use ACOS function in Excel to **find the inverse of cosine** of a number. 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.

## Syntax of ACOS Function

The syntax of the ACOS function is given below which contains the 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 which you have pass as argument. |

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

## Example to Find Inverse Cosine of a Number

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 if 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 are 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 requires 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

Hope, you like this post of how to use ACOS function in Excel. If you **have any query** regarding the tutorial,** please comment below.**

Also tell me,** which method you are using** to get the inverse cosine of a number in Microsoft Excel.

**Reference**

MS Office Support