The COS function is used in Excel to calculate the cosine of an angle in radians. It is a trigonometric function that helps you find the cosine value of an angle, which is useful in various mathematical and engineering calculations.

## Syntax

**COS(number)**

## Arguments

number | The angle in radians for which you want to find the cosine value. |

## How to use

To use the COS function, follow these steps:

1. Select the cell where you want the result to appear.

2. Type the following formula:

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=COS(number) |

3. Replace ‘number’ with the actual angle value in radians for which you want to calculate the cosine.

4. Press Enter to get the result.

Here are some examples of how to use the COS function:

**Example 1**: Calculate the cosine of 45 degrees (π/4 radians).

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=COS(PI()/4) |

**Example 2**: Find the cosine of 60 degrees (π/3 radians).

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=COS(PI()/3) |

**Example 3**: Calculate the cosine of 90 degrees (π/2 radians).

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=COS(PI()/2) |

Remember that the COS function works with radians, so you might need to convert degrees to radians using the PI() function when necessary.