Difference between revisions of "Ptolemy's Theorem"
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=== Definition === | === Definition === | ||
| − | Given a cyclic quadrilateral <math>ABCD</math> with side lengths <math>{a},{b},{c},{d}</math> and diagonals <math>{ | + | Given a cyclic quadrilateral <math>ABCD</math> with side lengths <math>{a},{b},{c},{d}</math> and diagonals <math>{e},{f}</math>: |
| − | <math>ac+bd= | + | <math>ac+bd=ef</math> |
Revision as of 13:02, 18 June 2006
Ptolemy's theorem gives a relationship between the side lengths and the diagonals of a cyclic quadrilateral; it is the equality case of the Ptolemy inequality.
Definition
Given a cyclic quadrilateral 
with side lengths 
and diagonals 
:
