# A to Z of Excel Functions: The COS Function

6 November 2017

**The COS function**

Not to be confused with cos lettuce, this function returns the cosine of the given angle. For those of you with more important things to do during your trigonometry lessons (like sleeping), that denotes the ratio of the adjacent side of a triangle divided by its hypotenuse (subject to sign considerations), viz.

The **COS **function employs the following syntax to operate:

**COS(number)**

The **COS** function has the following arguments:

**number:**this is required and represents the angle in radians for which you want the cosine.

It should be further noted that if the angle is in degrees, you should multiply the angle by **PI()/180** or else use the **RADIANS** function to convert the angle to radians.

Please see my example below:

*We’ll continue our A to Z of Excel Functions soon. Keep checking back – there’s a new blog post every other business day.*

*A full page of the function articles can be found here. *