COS Function in Excel: Cosine of an Angle

⏱ 1 min readUpdated 28 September 2026

MathLevel: IntermediateAvailable in: Excel 2007+

In this article
  1. Syntax
  2. Examples
  3. Example 1
  4. Related functions

COS also expects radians. Seasonal models sometimes use SIN and COS of the month to capture yearly cycles.

Syntax

=COS(number)
Argument What it means
number Angle in radians.

Examples

Example 1

=COS(2*PI()*MONTH(A2)/12)

A smooth yearly-cycle feature for a forecast model.

SIN · PI

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