In this article, we are going to discuss the Excel **COS** function, its uses, how to use it with degrees, COS square, why COS 90 is not zero, and how to fix it when it returns wrong outputs.

The **COS** function is used to determine the cosine of angles in Excel. By default, the **COS function** accepts the angles in radians. However, with the help of the other functions, you can insert angles both in radians as well as degrees. After finishing this article you will know everything about the COS function.

The above screenshot is an overview of the article, representing a few applications of the **COS** function in Excel. You’ll learn more about the methods along with the other functions to use the **COS** function precisely in the following sections of this article.

## Introduction to the COS Function

**Function Objective:**

**The COS function is used to determine the cosine of angles in Excel.**

**Syntax:**

*COS(number)*

**Arguments Explanation:**

Argument | Required/Optional | Explanation |
---|---|---|

number |
Required | Angle in radians to calculate the cosine of the given angle. |

**Return Parameter:**

**Cosine value of the given angles.**

## How to Use the COS Function in Excel: 2 Examples

Depending on the input values, the usage of the **COS** function falls into two main categories. The first one is input angles in radians which is the default angle metric for the **COS** function. The second one is angled in degrees. In the following sections, we will discuss both of the categories one by one.

We will also discuss the **COS** function in Excel **VBA**. So, without having any further discussion, let’s jump straight into all of the examples one by one.

### 1. Use COS Function in Excel for Angles in Radians

When you want to insert angles in radians, then the usage of the **COS** function is super easy. Because the **COS** function can work with the angles in radians by default. Anyways follow the steps below to see how to use the **COS** function for angles in radians.

**🔗 Steps:**

❶ Select cell **C5** ▶ to store the formula result.

❷ Then enter the formula:

`=COS(B6)`

❸ Now press the **ENTER** button ▶ to execute the formula.

❹ Finally, finish the whole process the dragging the **Fill Handle** icon to the end of the Cosine column.

That’s all you need to do. Anyways, when you are done with all the steps mentioned above, you will see the end result as in the picture below:

As we can see in the above picture, the cosine of the given angles is long fraction values. It’s not always convenient to use.

So, if you want you can trim those long numbers into your own convenience using the **ROUND** **function**. All you need to do is:

❶ Select cell **D5** ▶ to store the formula result.

❷ Then enter the formula:

`=ROUND(C5,2)`

❸ Now press the **ENTER** button ▶ to execute the formula.

❹ Finally, finish the whole process the dragging the **Fill Handle** icon to the end of the Cosine column.

That’s all you need to do. Anyways, when you are done with all the steps mentioned above, you will see the end result as in the picture below:

### 2. Use COS Function in Excel for Angles in Degrees

When you have angles in degrees, then to calculate the cosine of the angles you have to perform some extra task. That is to convert the angle from degree to radian. As **COS** function accepts only angles in radians.

So we can convert the angles in degrees in two different ways. The first one is using the **RADIAN **function. This is a built-in function inside Microsoft Excel that you can convert angles in degrees into angles in radians within a bleak of an eye.

Now the below steps will guide you to do so.

**🔗 Steps:**

❶ Select cell **C5** ▶ to store the formula result.

❷ Then enter the formula:

`=COS(RADIANS(B5))`

❸ Now press the **ENTER** button ▶ to execute the formula.

❹ Finally, finish the whole process the dragging the **Fill Handle** icon to the end of the Cosine column.

That’s all you need to do. Anyways, when you are done with all the steps mentioned above, you will see the end result as in the picture below:

**Alternative Conversion Method**

There’s another way to convert the angles in** degrees** into angles in **radians**. All you need to do is multiply the angles with **PI()/180**. Lemme show you the whole process step by step:

**🔗 Steps:**

❶ Select cell **C5** ▶ to store the formula result.

❷ Then enter the formula:

`=COS(B5*PI()/180)`

❸ Now press the **ENTER** button ▶ to execute the formula.

**Fill Handle** icon to the end of the Cosine column.

As we can see in the above picture, the cosine of the given angles is long fraction values. It’s not always convenient to use.

So, if you want you can trim those long numbers into your own convenience using the **ROUND** function. All you need to do is:

❶ Select cell **D5** ▶ to store the formula result.

❷ Then enter the formula:

`=ROUND(C5,2)`

❸ Now press the **ENTER** button ▶ to execute the formula.

**Fill Handle** icon to the end of the Cosine column.

## Things to Remember

📌 The **COS** function expects the angles in radians.

📌 For the angles in degrees, you must convert the angles into radians either by using the **RADIAN** function or multiplying the angle with **PI()/180**.

**Download the Practice Workbook**

You are recommended to download the Excel file and practice along with it.

## Conclusion

To sum up, we have discussed everything there is to know about the Excel **COS** function in this article. You are recommended to download the practice workbook attached along with this article and practice all the methods with that. And don’t hesitate to ask any questions in the comment section below. We will try to respond to all the relevant queries asap.