ACOT Function in Excel: Inverse Cotangent

ACOT Function in Excel: Inverse Cotangent 1
⏱ 1 min readUpdated 5 October 2026

Maths & trigLevel: ExpertAvailable in: Excel 2013+

In this article
  1. Syntax
  2. Examples
  3. Example 1
  4. ACOT in practice
  5. Where you will use it
  6. Worked example
  7. Mistakes people make
  8. Related functions

ACOT returns the angle (0 to π) whose cotangent is x.

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Syntax

=ACOT(number)
Argument What it means
number Value (angles in radians)

Examples

Example 1

=ROUND(ACOT(A2),5)

Result: 0.7854. See the worked example table below for more cases.

ACOT in practice

Where you will use it

  • Engineering and physics formulas
  • Geometry and surveying
  • Coursework

Worked example

xFormulaResult
1=ROUND(ACOT(A2),5)0.7854
0=ROUND(ACOT(A3),5)1.5708
-1=ROUND(ACOT(A4),5)2.35619

Results calculated in Excel.

Mistakes people make

MistakeWhat to do instead
Degrees instead of radiansWrap in RADIANS for angles
Out-of-range input#NUM! or #DIV/0!

SIN · COS · TAN

📚 Part of the free Excel course: Beginner → Expert · Try it in the Formula Lab or ask the AI Helper.

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