ACOT Function in ONLYOFFICE Spreadsheet Editor: Syntax, Examples and Compatibility

The named function and the syntax below are in the current, unversioned English ONLYOFFICE Docs Spreadsheet Editor documentation reviewed on 13 October 2026 (UTC). This is documentary support for the current reference, not a successful execution test in ONLYOFFICE Docs/web or Desktop Editors, and it is not a claim of support in all earlier versions, hosting editions, mobile apps, or imported Excel workbooks. The Docs changelog lists version 10.0.0 dated 10 October 2026; that changelog does not identify these particular functions as newly introduced in 10.0. Desktop release history is maintained separately, and no first-supported Desktop/web version has been established for this function.

Verification labels used in this guide: vendor documented = stated in a linked ONLYOFFICE source; independently calculated expectation = calculated outside ONLYOFFICE using mathematics/Python; native result = none obtained. Illustrations/screenshots were not fabricated or substituted for actual tests.

=ACOT(number)

• number (required, numeric): Required numeric cotangent value. There is no second argument and no default. The vendor does not specify a finite numeric bound for this parameter in its ACOT reference.
• Argument order: one positional numeric argument only. Optional arguments/defaults: none.
• Return type: numeric real value for an in-domain mathematical input; the exact cell display can vary with number format.
• Mathematical domain: All finite real numeric inputs are mathematically permitted, including zero and negative values. Native coercion of blanks/text and extraordinary magnitudes was not tested.
• Principal range / behaviour: The vendor describes a principal angle from 0 to π radians. Mathematically, finite real inputs produce angles strictly between those endpoints; both endpoints are approached but not attained.
• Units: The result is in radians. Wrap the result in DEGREES(...) for a display in degrees. Unlike inverse hyperbolic functions, the output represents a circular angle.

Mathematical interpretation: For real x, principal arccot(x) = π/2 − arctan(x). This equivalent mathematical expression is used only for independent result checking; it is not evidence of vendor implementation.

1. Create an empty spreadsheet in the ONLYOFFICE Spreadsheet Editor, using its English formula language for the formulas shown.
2. Enter the numbers exactly as shown in the Input in A column below, beginning in A2 and going down one row per example; do not include the units, symbols, or quotation marks as part of the values.
3. In B2, enter =ACOT(A2), press Enter, and fill the formula down the column. Numeric cells can be formatted to show ten decimal places.
4. Compare your result to the independently calculated expectation, allowing for display rounding and floating-point arithmetic. This guide does not claim that steps 1–3 were executed in either ONLYOFFICE product.

Interpreting the table: values are independent mathematical expectations rounded for readability, not screenshots or verified calculations performed in ONLYOFFICE. Values at very small magnitude may display in scientific notation when the worksheet format changes.

1. Acute-angle triangle: adjacent run 3, opposite rise 4

Set up: Enter D2 = 3 and E2 = 4, then enter =DEGREES(ACOT(D2/E2)) in F2.

Expected output: 53.1301023542° (independently calculated, not native-tested).

Why it works: For positive sides, the cotangent ratio is adjacent/opposite. The inverse returns the acute interior angle. For a signed or full-circle bearing, this principal-value function alone cannot determine every quadrant.

2. Negative cotangent and the principal quadrant

Set up: Enter D3 = -1; in F3 enter =DEGREES(ACOT(D3)).

Expected output: 135° (independently calculated, not native-tested).

Why it works: A negative cotangent ratio is mapped to the second quadrant by the 0–π principal-value convention, not to −45°.

3. Safe ratio formula for changing row data

Set up: Set D4 = 3, E4 = 4, and enter =IF(E4=0,"Cannot divide by zero",DEGREES(ACOT(D4/E4))) in F4.

Expected output: 53.1301023542° (independently calculated, not native-tested).

Why it works: The IF guard addresses division by zero before forming adjacent/opposite. Verify the exact display locale of quotation marks and formula separators in your editor.

4. Check a reverse calculation

Set up: Enter =COT(ACOT(2)) in F5.

Expected output: 2 (within floating-point precision) (independently calculated, not native-tested).

Why it works: Composing COT with ACOT recovers the cotangent input for ordinary finite values. This is a mathematical expected output, not a native cross-function test.

5. Convert and round for a report

Set up: Enter =ROUND(DEGREES(ACOT(0.5)),2) in F6.

Expected output: 63.43 (independently calculated, not native-tested).

Why it works: ROUND returns a numerically rounded result for reporting; formatting alone would change only its appearance. The ACOT mathematical definition is unchanged.

Error-code caution: ONLYOFFICE documentation for this function does not establish exact error strings for every invalid input, coercion, overflow, or version. Thus this guide does not assert #NUM!, #DIV/0!, or other codes as observed in ONLYOFFICE. Record actual native outputs and version/edition before relying on undocumented error behavior.

The examples use English function names, decimal points and (where needed) comma-separated arguments. The official Insert Function guide explains that manual formulas begin with = and that arguments are separated by commas in its English instructions. The Advanced Settings page documents configurable formula language and regional decimal/thousands separators. Neither source establishes how this exact function was spelled or evaluated for every locale. Do not rewrite formulas using a different locale based only on habits from another spreadsheet program.

The vendor distinguishes the web/Docs editor from Desktop Editors and maintains separate release changelogs. The current function page does not state a first-supported version or guarantee parity across historical installations. Version-sensitive behaviour, real error results, large-value precision, workbook imports, mobile editions, and localized syntax therefore require native verification. A release-note mention of a related Spreadsheet Editor improvement must not be mistaken for a function introduction.

• COT function — vendor function reference.
• DEGREES function — vendor function reference.
• IF function — vendor function reference.
• ROUND function — vendor function reference.
• Insert functions in ONLYOFFICE Spreadsheet Editor — function-selection, autocomplete and entry workflow.
• Spreadsheet Editor advanced settings — formula language, regions, and separators.

Is ACOT the same as ATAN?

No. ACOT has a different principal branch. In particular ACOT(−1) is 135°, whereas the ordinary arctangent principal value of −1 is −45°.

Can ACOT accept zero?

Yes mathematically: inverse cotangent of zero is π/2 radians, or 90°. This is supported by the documented principal inverse-cotangent definition.

Does ACOT return degrees?

No. Its official reference specifies radians. Convert with the separately documented DEGREES function.

Verification limitations: Native Docs/web and Desktop execution, localized parsing, extreme-value precision, historical editions and runtime error behavior were not tested.