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Ptolemy's theorem

theorem
Class type of: Casey’s theorem Q459547

Facts

9 properties
Instance of
theorem
Publication date
100[5]
Subclass of
Casey’s theorem
Part of
list of theorems[4]
Copyright status
public domain, public domain[9]
Maintained by WikiProject
WikiProject Mathematics[8]
Named after
Ptolemy[3]
Statement describes
cyclic quadrilateral[6]
Studied by
Euclidean geometry[7]
🏷️ Also known as
en Ptolemy's theorem ar مبرهنه بطليموس ar نظرية بطليموس ar مبرهنة بطليموس de Satz von Ptolemäus el Θεώρημα Πτολεμαίου es Teorema de Ptolomeo fa قضیه بطلمیوس fa قضیهٔ بطلمیوس fi Ptolemaioksen epäyhtälö fi Ptolemaioksen lause fr théorème de Ptolémée he משפט תלמי hi प्तोलेमी का प्रमेय hu Ptolemaiosz-tétel it Teorema di Tolomeo ja トレミーの定理 ja プトレマイオスの定理 ko 프톨레마이오스의 정리 ko 프톨레마이오스 정리
🔖 Identifiers · 6
Freebase ID
/m/057r6r
Great Russian Encyclopedia portal ID
teorema-ptolemeia-1feafe
MathWorld ID
PtolemyInequality
Metamath statement ID
ptolemy
Microsoft Academic ID (discontinued)
82738788
PlanetMath ID
PtolemysTheorem

Report an error or request removal Lineage (PROV-JSON)

🔗 Connections
Copyright status 2
public domain, public domain
Created notable works 1
Ptolemy
Instance of 1
theorem
Maintained by WikiProject 1
WikiProject Mathematics
Named after 1
Ptolemy
Part of 1
list of theorems
Statement describes 1
cyclic quadrilateral
Studied by 1
Euclidean geometry
Subclass of 1
Casey’s theorem
← Has characteristic 1
quadrilateral
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Summary

Ptolemy's theorem is a theorem[1]. It is a type of Casey’s theorem[2].

Related Entities

Ptolemy public domain

References

Programmatic citations — every numbered marker resolves to a verifiable graph row below.

Direct Wikidata claims

  1. [3] ↑ . wikidata.org.
  2. [2] ↑ . wikidata.org.
  3. [4] ↑ . wikidata.org.
  4. [5] ↑ . wikidata.org.
  5. [6] ↑ . wikidata.org.
  6. [7] ↑ . wikidata.org.
  7. [8] ↑ . wikidata.org.
  8. [9] ↑ . wikidata.org.

Class ancestry

  1. [1] ↑ . Wikidata. wikidata.org.

📑 Cite this page

Use these citations when quoting this entity in research, articles, AI prompts, or wherever provenance matters. We aggregate Wikidata + Wikipedia + authoritative open-data sources; the stitched, scored, cross-referenced view is what 4ort.xyz contributes.

APA 4ort.xyz Knowledge Graph. (2026). Ptolemy's theorem. Retrieved November 3, 2026, from https://4ort.xyz/entity/ptolemy-s-theorem
MLA “Ptolemy's theorem.” 4ort.xyz Knowledge Graph, 4ort.xyz, 3 Nov. 2026, https://4ort.xyz/entity/ptolemy-s-theorem.
BibTeX @misc{4ortxyz_ptolemy-s-theorem_2026, author = {{4ort.xyz Knowledge Graph}}, title = {{Ptolemy's theorem}}, year = {2026}, url = {https://4ort.xyz/entity/ptolemy-s-theorem}, note = {Accessed: 2026-11-03}}
LLM prompt According to 4ort.xyz Knowledge Graph (aggregator of Wikidata, Wikipedia, and authoritative open-data sources): Ptolemy's theorem — https://4ort.xyz/entity/ptolemy-s-theorem (retrieved 2026-11-03)

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Edit History

Rolling log of changes to this entity's Wikidata record. Values shown reflect the current state of each edited property — follow the history link to see the precise diff for any edit.

  1. 4d ago · Wsikik · 2026-10-31 view diff on Wikidata ↗
    Maintained by WikiProject → WikiProject Mathematics
    Part of → list of theorems
    Wikipedia languages → ['ar', 'bg', 'ca', 'ckb', 'commons', 'de', 'el', 'en', 'es', 'fa', 'fi', 'fr', '
    Named after → Ptolemy
    + 12 other properties edited (see Wikidata diff for full list)
    "/* wbsetdescription-add:1|ca */ relaciona els costats i diagonals d'un quadrilàter amb vèrtexs en una circumferència"
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