COS Function
Returns the cosine of an angle given in radians.
Syntax
Parameters
| Parameter | Description | Required |
|---|---|---|
| number | The angle, in radians, for which you want the cosine. | Required |
Basic Example
Cosine of 60 degrees
=COS(RADIANS(60))RADIANS(60) converts to π/3; the cosine of π/3 is 0.5.
Advanced Examples
Example 1: Cosine of 0
Baseline check.Cosine of zero radians.
=COS(0)Example 2: Cosine of π
Half turn.Use PI() for π.
=COS(PI())How COS Works
COS computes the cosine of an angle measured in radians. The function is periodic with period 2π, so COS(x) = COS(x + 2πk) for any integer k.
Important Notes & Limitations
The angle must be in radians; degrees must be converted with RADIANS or PI()/180.
Results are approximate due to floating-point math.
COS cannot directly take degrees, unlike some calculator conventions.
Common Errors & Fixes
Unexpected large/small resultAngle was supplied in degrees instead of radians.Fix: Wrap the angle in RADIANS() or multiply by PI()/180.
#VALUE!Non-numeric argument.Fix: Supply a numeric angle.
Download Practice File
COS
cosPractice COS with Real Data
Download a sample CSV file with pre-populated data and practice exercises for the COS function. Works in both Excel and Google Sheets.
File format: CSV (comma-separated values) - opens in Excel, Google Sheets, and all spreadsheet apps