Short answer: Geometry notation lives in the mathematical operators block, so none of these has a Windows Alt code except the degree sign. Copy them from the keys below, or type the hex code then Alt + X in Word — 2220 gives ∠. The one to get right is the triangle: △ U+25B3, not the Greek delta.
Tap to copy
Not sure which triangle or which perpendicular sign a document is using? The Symbol Identifier reports the exact code point.
The full set
| Symbol | Meaning | Official Unicode name | Code point | Word |
|---|---|---|---|---|
| ∠ | Angle | Angle | U+2220 | 2220 + Alt + X |
| ∡ | Measured angle | Measured angle | U+2221 | 2221 + Alt + X |
| ∟ | Right angle | Right angle | U+221F | 221F + Alt + X |
| ⊥ | Perpendicular to | Up tack | U+22A5 | 22A5 + Alt + X |
| ∥ | Parallel to | Parallel to | U+2225 | 2225 + Alt + X |
| ∦ | Not parallel to | Not parallel to | U+2226 | 2226 + Alt + X |
| ≅ | Congruent to | Approximately equal to | U+2245 | 2245 + Alt + X |
| ≇ | Not congruent to | Neither approximately nor actually equal to | U+2247 | 2247 + Alt + X |
| ∼ | Similar to | Tilde operator | U+223C | 223C + Alt + X |
| ≡ | Identical to | Identical to | U+2261 | 2261 + Alt + X |
| △ | Triangle | White up-pointing triangle | U+25B3 | 25B3 + Alt + X |
| □ | Square | White square | U+25A1 | 25A1 + Alt + X |
| ⌒ | Arc | Arc | U+2312 | 2312 + Alt + X |
| ⊙ | Circle with centre | Circled dot operator | U+2299 | 2299 + Alt + X |
| ° | Degrees | Degree sign | U+00B0 | Alt + 0176 |
| ′ | Arcminutes | Prime | U+2032 | 2032 + Alt + X |
| ″ | Arcseconds | Double prime | U+2033 | 2033 + Alt + X |
The degree sign is the only one with an Alt code. Everything else sits above the Windows-1252 range the legacy Alt codes cover, so it’s hex plus Alt + X in Word, or copy. Degrees, minutes and seconds have their own guides at the degree symbol and the prime symbol — and note that arcminutes take a prime, never an apostrophe.
Two names in that table will surprise you, and both are worth knowing.
⊥ is officially called “up tack”
The character everyone uses for perpendicular is U+22A5, and its official Unicode name is UP TACK — it comes from logic and lattice theory, where it means “bottom” or “false”.
There is a separate character actually named PERPENDICULAR, at U+27C2. It looks near-identical.
So which should you use? U+22A5, without hesitation. It’s what LaTeX’s \perp produces, what mathematical typesetting has used for decades, and what fonts reliably cover. U+27C2 is the technically-named one and the practically wrong one — poorer font support, unfamiliar to every tool that processes maths. This is a case where the convention beats the name.
The same pattern applies to ≅: the congruence sign is U+2245, whose official name is APPROXIMATELY EQUAL TO. Unicode named it for its shape and general use; geometry adopted it for congruence. Use U+2245 and ignore the name.
Which triangle? There are three
This is the most common real error in typed geometry, and the three characters are genuinely different:
| Character | Code point | Official name | What it’s for |
|---|---|---|---|
| △ | U+25B3 | White up-pointing triangle | Geometry — the shape |
| ∆ | U+2206 | Increment | Change in a quantity — Δx |
| Δ | U+0394 | Greek capital letter delta | The Greek letter |
For “triangle ABC”, use △ U+25B3. The increment sign belongs in calculus, and the Greek letter belongs in Greek text or as a named variable — see the delta symbol and the Greek alphabet.
They look nearly identical in most fonts, and nothing warns you. The consequences are the ordinary ones: a search for triangles misses two thirds of them, a screen reader announces “increment” in the middle of a geometry proof, and sorting scatters them.
Normalisation won’t rescue you here. None of the three merges under any Unicode normalisation form — they’re separate characters that happen to share a shape, not variant spellings of one character.
The parallel sign has a smaller version of the same problem: ∥ U+2225 PARALLEL TO is the operator, while ‖ U+2016 DOUBLE VERTICAL LINE is punctuation and || is two pipe characters. All three render similarly; only the first is the mathematical symbol.
Windows
- In Word: type the hex code, then Alt + X.
2220becomes ∠. Press Alt + X again to reverse it. - Degrees: hold Alt and type 0176 on the numeric keypad — the only Alt code in the set.
- Character Map: run
charmap, tick Advanced view, set Go to Unicode to2220. The block you want is Mathematical Operators. - Equation editor: press Alt + = for a proper equation field. For real mathematics this is the better route — the symbols get correct spacing and italics, which matters in anything you’ll print. See symbols in Word.
Mac
No Option shortcut exists for any of these, so don’t hunt for one.
- Unicode Hex Input: add it in System Settings → Keyboard → Input Sources, then hold Option and type 2220. All of these are in the Basic Multilingual Plane, so this works throughout.
- Character Viewer: Control + Command + Space, then search “angle” or “perpendicular”. Searching by Unicode name is more reliable than browsing the categories.
Linux
Ctrl + Shift + U, type 2220, then Enter or Space — the GNOME-documented sequence. More in typing symbols on Linux.
Google Docs and LaTeX
- Google Docs: Insert → Special characters, then search by name or paste the code point. For anything with structure, Insert → Equation handles spacing properly. See symbols in Google Docs.
- LaTeX: this is where geometry notation is least painful, because every symbol has a name:
latex
\angle ABC \qquad AB \perp CD \qquad AB \parallel CD
\triangle ABC \cong \triangle DEF \qquad \triangle ABC \sim \triangle XYZ
30^\circ \qquad 45' \qquad 30''Note that \perp produces U+22A5 and \triangle produces the geometric triangle — LaTeX makes the right choices for you, which is a good argument for using it whenever the mathematics gets beyond a sentence. More in LaTeX math symbols.
In HTML, use numeric references: ∠ (∠), ⊥ (⊥), ∥ (∥), ≅ (≅), △ (△), ° (°).
Writing it properly
A few conventions that make typed geometry readable:
- Angle measure:
m∠ABC = 45°— the m prefix means “the measure of”, so the angle symbol names the angle and m∠ names its size. - Degrees, minutes, seconds:
30° 15′ 20″— prime and double prime, never apostrophe and quotation mark. Straight quotes here are the single most common typo in typed geometry. - Similar vs congruent: ∼ means the same shape, ≅ means the same shape and size. Related comparison signs are in comparison symbols.
- Don’t fake an overline. Line segment notation needs a bar over the letters, which is a combining character (U+0305) rather than a symbol you can type inline. In Word or LaTeX, use the equation editor’s overline — a hyphen row underneath isn’t the same thing and won’t survive a copy-paste.
Accessibility
Screen readers announce these by Unicode name, which for two of them is actively misleading: ⊥ is read as “up tack” and ≅ as “approximately equal to”, neither of which is what your proof means. The triangle problem is worse — ∆ U+2206 is announced as “increment” in the middle of a geometry sentence.
Not the same as ≈: see approx sign.
So: use the right characters, because the names are what a listener hears. And for any statement carrying real meaning, write it in words on first use — “angle ABC measures 45 degrees” — and let the notation follow. How screen readers pronounce symbols covers the pattern.
Troubleshooting
| Problem | Fix |
|---|---|
| Alt code doesn’t work for ∠ or ⊥ | There isn’t one. Only ° has an Alt code (0176). Use hex + Alt + X in Word. |
| Triangle looks wrong or sorts oddly | You may have ∆ U+2206 or Δ U+0394 instead of △ U+25B3. Check the code point. |
| Symbol shows as a box | Font gap. Cambria, Calibri and Noto Serif all cover Mathematical Operators. |
| Spacing looks cramped in Word | Use the equation editor (Alt + =); inline characters don’t get mathematical spacing. |
| Arcminutes look like apostrophes | They probably are. Use ′ U+2032 and ″ U+2033. |
| Perpendicular sign missing from a font | You may have U+27C2. Switch to U+22A5, which has far wider coverage. |
| Overline over a segment won’t copy | It’s a combining mark, not a symbol. Use the equation editor’s overline instead. |
Recap
| You need | Use |
|---|---|
| Angle | ∠ U+2220 |
| Perpendicular | ⊥ U+22A5 — not U+27C2 |
| Parallel | ∥ U+2225 — not two pipes |
| Congruent | ≅ U+2245 |
| Triangle | △ U+25B3 — not Δ |
| Degrees | °, Alt + 0176 |
| Anything structured | Word’s equation editor, or LaTeX |
Frequently asked questions
How do I type the angle symbol ∠?
In Word, type 2220 then press Alt + X. On a Mac, enable Unicode Hex Input and press Option + 2220. There’s no Windows Alt code — the degree sign is the only geometry symbol that has one.
Which triangle symbol should I use in geometry?
△ U+25B3, the white up-pointing triangle. ∆ U+2206 is the increment sign used for change in a quantity, and Δ U+0394 is the Greek letter. All three look similar and none is interchangeable.
Is ⊥ really called “up tack”?
Yes. U+22A5’s official Unicode name is UP TACK, from logic and lattice theory. There’s a separate character named PERPENDICULAR at U+27C2, but U+22A5 is what LaTeX produces, what typesetting convention uses and what fonts actually cover — so use it anyway.
Why is the congruence sign named “approximately equal to”?
Unicode named U+2245 for its shape and general usage, and geometry adopted it for congruence. It’s the correct character for congruent figures despite the name.
Do geometry symbols have Windows Alt codes?
Only the degree sign, at Alt + 0176. The rest live in the Mathematical Operators block, well above the range legacy Alt codes reach, so use hex plus Alt + X in Word or copy them.
How do I write angle measures correctly?
Use m∠ABC for the measure of an angle, and prime and double prime for minutes and seconds — 30° 15′ 20″. Apostrophes and quotation marks are the most common typo in typed geometry.
Written by Igor R. Tested on Windows 11, macOS, Linux, Word, Google Docs and LaTeX. Last updated September 2026. Symbol code points follow the Unicode Standard.