The COS function in Excel is used to calculate the cosine of a given angle, which should be provided in radians. If you have an angle in degrees, you’ll need to convert it to radians first. Here’s how you can use the COS function:
Basic Usage
COS(number)
- COS Function Syntax:
- number: The angle in radians for which you want the cosine.
- Calculate Cosine:
If you already have an angle in radians and want to find the cosine, enter a formula like:
=COS(1.0472)
This would return the cosine of approximately 60 degrees (1.0472 radians).
Using Degrees
Since angles in trigonometric functions in Excel need to be in radians, you might need to convert degrees to radians first.
- Degree to Radian Conversion:
Use the `RADIANS` function to convert degrees to radians.
RADIANS(degrees)
Or, you can convert manually by multiplying by π/180:
=degree * (PI()/180)
- Combine with COS:
To find the cosine of 60 degrees:
=COS(RADIANS(60))
Or manually convert degrees to radians using π:
=COS(60 * PI() / 180)
Example
Assume you have the angle in degrees in cell `A1` and you want to find the cosine of that angle:
=COS(RADIANS(A1))
- Place this formula in another cell:
Tips
- Accuracy: Ensure your angle is correctly converted to radians if it’s initially in degrees.
- Excel’s PI() Function: Use `PI()` to get the value of π for precision.
The COS function is straightforward once you understand the requirement for radians and how to convert from degrees if necessary.
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