Statements (17)
| Predicate | Object |
|---|---|
| gptkbp:instanceOf |
gptkb:mathematical_concept
|
| gptkbp:appliesTo |
cyclic quadrilateral
|
| gptkbp:field |
gptkb:geometry
|
| gptkbp:firstDescribed |
gptkb:Almagest
gptkb:Ptolemy |
| gptkbp:form |
AC·BD = AB·CD + AD·BC
|
| gptkbp:generalizes |
triangle inequality for cyclic quadrilaterals
|
| gptkbp:hasConverse |
If a quadrilateral satisfies the Ptolemy equality, it is cyclic.
|
| https://www.w3.org/2000/01/rdf-schema#label |
Ptolemy's theorem
|
| gptkbp:namedAfter |
gptkb:Claudius_Ptolemy
|
| gptkbp:relatedTo |
gptkb:butter
gptkb:law_of_cosines |
| gptkbp:sentence |
In a cyclic quadrilateral, the product of the two diagonals equals the sum of the products of the two pairs of opposite sides.
|
| gptkbp:usedIn |
gptkb:Euclidean_geometry
trigonometry |
| gptkbp:bfsParent |
gptkb:Claudius_Ptolemy
|
| gptkbp:bfsLayer |
5
|