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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:


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.