TAN Function in ONLYOFFICE Spreadsheet Editor: Radians, Slope, and Examples

=ROUND(TAN(RADIANS(45)),6) has independently expected result 1; a 45° incline rises about one unit for every one unit of horizontal run. All results here are mathematical expectations independently calculated, not results observed in an ONLYOFFICE installation.

Tangent is the ratio of sine to cosine when cosine is not zero, so the mathematical function models slope and can grow arbitrarily large near vertical angles. The ONLYOFFICE TAN reference explicitly identifies its argument as an angle in radians, unlike its shorter COS entry.

Typical applications include spreadsheet diagrams, engineering classroom exercises, geometry models and numerical cross-checks. Avoid claiming a universal finite bound: tangent can have arbitrarily large magnitude as the angle approaches an odd multiple of π/2.

=TAN(number)

The name, spelling, one-argument order and the specific documented domain/unit details above come from the official ONLYOFFICE TAN reference, checked 2026-10-13 UTC. A cell reference such as TAN(A2) is ordinary formula usage. Coercion of arbitrary strings, blank cells, error values, and exact handling of floating-point underflow/overflow are not fully specified in the short vendor article and are not asserted here.

The TAN function reference was checked on 2026-10-13 (UTC); it is a function-level English-language help article without a first-supported-version matrix. The function is documented for ONLYOFFICE Spreadsheet Editor, but that alone does not prove identical behaviour in every web Docs, desktop, offline or self-hosted release. The official Docs changelog and Desktop Editors changelog are separate; neither establishes the earliest build supporting the precise formula from the references checked here. No native Desktop or web execution was available in this run.

The official function insertion guide describes typing a formula or choosing Home / Formula → Insert Function, and notes the Shift+F3 shortcut. The Advanced Settings reference documents independent Formula Language, Region, and decimal/thousands separator settings. The examples below use English names, decimal periods, and commas between ROUND arguments. Check the actual editor’s formula language and syntax suggestions when moving formulas across locales; localized aliases and separators have not been native-tested. In a one-argument TAN(...) call, there is no function-argument separator inside the call.

Cross-product compatibility: this guide shows the official ONLYOFFICE English syntax only. Other spreadsheet products may have similarly named functions; their runtime error coercion, locale, precision, and version support are not evidence for ONLYOFFICE. A file exported between products requires an explicit test in each destination environment. No claim of exact compatibility is made here.

1. Open a blank workbook. In A1, type Input (number or formula), in B1 type TAN result, and in C1 type Rounded check.
2. Copy the input expressions in the A column shown below. If an input starts with =, enter it as a formula (rather than text); a bare numeric entry is typed as a number. Do not enter Markdown backticks.
3. In B2 enter =TAN(A2); in C2 enter =ROUND(B2,6) in English-language formula notation.
4. Fill B2:C2 downward through row 13. The row-specific formulas below show what filling down should produce.
5. Compare column C against the independently calculated results. Differences require checking the release, language, input units, and rounding. No native execution or screenshots are claimed.

Validation method: Python math functions independently calculated each raw expected number and then prepared a six-decimal display value. Tiny floating-point differences are possible; the six-decimal display is an editorial expectation, not a promised bitwise result for every installation.

Each expression below is independent; enter it into an empty cell. The ROUND(...,6) wrapper makes comparisons readable in the English-language reference syntax. The listed outputs are calculated results, not screenshots or native application observations.

Convert roof pitch into vertical rise

Enter a horizontal run of 10 in D2, a degree angle of 30 in E2, and =D2*TAN(RADIANS(E2)) in F2. The independently expected rise is approximately 5.773503. To express a slope as a grade percentage, enter =ROUND(100*TAN(RADIANS(E2)),2) in G2; expected 57.74. These are geometrical calculations; for construction, do not use them in place of approved design measurements or applicable codes.

Verify the ratio on an ordinary angle

Set D3 to 30 and enter =ROUND(TAN(RADIANS(D3)),6) in E3. Enter =ROUND(SIN(RADIANS(D3))/COS(RADIANS(D3)),6) in F3. Both values are independently expected 0.57735. This identity does not justify division when the cosine is zero or extremely close to zero. It is a mathematical cross-check, not an observation that either formula was executed in ONLYOFFICE.

Periodicity and scale

The tangent repeats after a half-turn: =ROUND(TAN(RADIANS(45)+PI()),6) has independently expected 1. Extremely steep input angles amplify small input errors. A formula that first rounds the angle can be inappropriate close to 90° or 270°, where tangent is singular. Use a sensible input tolerance and flag near-vertical measurements before interpreting the output.

• Degrees supplied directly: The documented parameter uses radians. =TAN(45) is not the same as =TAN(RADIANS(45)).
• Apparent enormous result at 90°: Mathematically tan(π/2) is undefined; PI() is approximated in finite precision. In numerical software a very large finite value rather than a particular error is possible. The ONLYOFFICE reference does not specify the exact target-version result; native test required.
• Negative values: A descending slope, or a second/fourth-quadrant angle, can legitimately have a negative tangent.
• Reported slope versus angle: TAN returns a ratio, not a degree value or percent. Multiply by 100 for percent grade when appropriate.
• Coercion and error messages: Exact handling of text, blank cells and overflow is not documented in the short official TAN page. Do not assert a specific error code for the target release without testing.
• Localized formulas and build differences: Use the editor’s Formula Language and Region settings and validate against the specific Docs/Desktop version.

• TAN — official ONLYOFFICE function reference (syntax, one argument and vendor-described purpose).
• RADIANS — convert degree angles to radians and DEGREES — convert radian angles to degrees (vendor-documented converter directions and syntax).
• PI — mathematical constant (vendor-documented zero-argument function).
• SIN — sine reference, COS — cosine reference, TAN — tangent reference, and ACOS — arccosine reference (mathematically related operations; only the linked vendor claims are asserted).
• Inserting functions and Advanced Settings (editor steps and formula language/region settings).
• Docs changelog and Desktop Editors changelog (separate release tracks; not proof of uniform compatibility).

Official references were checked on 2026-10-13 UTC; they establish documented syntax, not native execution of the examples.

All outputs are independent mathematical expectations. Native ONLYOFFICE Desktop/web execution, exact runtime errors, localized parsing, historical release support and workbook interchange remain untested.