ACOS

The ACOS function returns the arccosine, or inverse cosine, of a number. It is useful for finding the angle whose cosine is the specified number, especially in trigonometry and geometry.

Syntax

=ACOS(number)

Number The cosine of the angle for which you want to find the arccosine.
Number The cosine of the angle for which you want to find the arccosine.

About ACOS

When you're dealing with angles and need to find the precise angle whose cosine matches a given number, the ACOS function in Excel comes to the rescue. It plays a key role in trigonometry and geometry, providing a straightforward method to determine the arccosine, or inverse cosine, of a specified number. This is particularly handy for various calculations involving angles and their corresponding trigonometric functions.

Examples

If you want to find the angle whose cosine is 0.5, you can use the ACOS function as follows: =ACOS(0.5). This will return the value of the angle in radians.

Questions

What does the ACOS function return?

The ACOS function returns the arccosine of the given number, which represents the angle in radians whose cosine equals the specified number.

What is the allowable range for the input number in the ACOS function?

The input number for the ACOS function must fall within the range of -1 to 1. If the input number is outside this range, the function will result in a #NUM! error.

Related functions

['COS'
'COSH'
'ASIN'
'ATAN']