# How to Use Excel COS Function with Degrees (2 Easy Ways)

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Cosine is a trigonometric operator. It is related to the angles created by a right-angle triangle. Excel offers a dedicated function named the COS function to evaluate the cosine value of an angle. But it does not take the angle in degree units but in radian units. In this article, we will show how to use Excel COS function with degrees.

## Excel COS Function Overview

• Summary

The COS function in Excel returns the value of the cosine operator of a particular angle. The angle that is delivered as the only function argument should be in radians.

• Generic Syntax

COS (number)

• Argument Description
ARGUMENT REQUIRMENT EXPLANATION
number Required This is the angle in radian units for which we will get the cosine value.

In this article, we will discuss two ways to convert degrees to radians and use them in the Excel COS function. Firstly, we will use the RADIANS function to directly convert the degrees into radian units. Then, we will use the PI function to transform degrees into radians.

The RADIANS function takes degrees as its units and then turns them into radian units. In this method, we will use it to convert degrees into radians and deliver them as the arguments of the COS function.

Steps:

• Firstly, select the C5 cell and write down the following formula,
`=COS(RADIANS(B5))`
• Then, hit Enter.

• Consequently, we will get the cosine value of the particular angel.
• Finally, move the cursor down to the last data cell and Excel will automatically fill the cells according to the formula.

Note:

• As we can see in the C10 cell the value of cos 90 degrees is not zero. But in practice, we know that it will be zero. This is because of the conversion mechanism of decimal numbers by Excel.

• To avoid it, write the following formula in the C10 cell,
`=ROUND(COS(RADIANS(B10)),12)`
• Then, hit Enter.

• As a result, Excel will automatically round the result to zero.

ðŸ”Ž Formula Breakdown:

• RADIANS(B10): This will turn the degrees in the B10 cell into radians.
• COS(RADIANS(B10)): This will return the cosine value for the radian angle supplied by the RADIAN function. This value will be very close to zero, 6.12574 E-17.
• ROUND(COS(RADIANS(B10)),12): The ROUND function will round the value up to 12 numbers and eventually return zero.

## 2. Applying PI Function

The PI function returns the value of pi, a constant number, up to 15 digits after the decimal point. In this instance, we will convert the degrees into radians using the PI function.

The formula to change the degree from radian will be,

Radian = ( Degree * Pi/180); Here, Pi= 3.14159265358979

Steps:

• To begin with, select the C5 cell and write down the following formula,
`=COS(B5*PI()/180)`
• After that, hit Enter.

• As a result, the cosine value of the particular angel will be in the C5 cell.
• Finally, lower the cursor down to the last data cell to get the values for the rest of the angles.

## How to Calculate Inverse Cosine in Excel

The inverse cosine of a number indicates the radian angle of a particular cosine value. Excel offers the ACOS function to calculate the inverse cosine value. The ACOS function takes numbers as its input and returns radian values.

Steps:

• To start with, select the C5 cell and write down the following formula,
`=ACOS(B5)`
• After that, hit the Enter button.

• As a result, the inverse cosine value will be in the C5 cell.
• Finally, lower the cursor down to the last data cell to get the values for the rest of the angles.

Note:

In the following image, we can see that the ACOS function is returning an error for the 1.5 and -2 values. This happens because the ACOS function returns a valid output only for numbers that fall in the range -1 to 1.

## Conclusion

In this article, we have discussed 2 ways to use the Excel COS Function with degrees. This will help users to calculate the cosine value of an angle expressed in degrees.