Butterfly theorem
From Wikipedia, the free encyclopedia
For the "butterfly lemma" of group theory, see Zassenhaus lemma.
The butterfly theorem is a classical result in Euclidean geometry, which can be stated as follows:
Let M be the midpoint of a chord PQ of a circle, through which two other chords AB and CD are drawn; AD and BC intersect chord PQ at X and Y correspondingly. Then M is the midpoint of XY.
 |
This geometry-related article is a stub. You can help Wikipedia by expanding it. |
[edit] External links
- Butterfly theorem, animated proof by Antonio Gutierrez from "Geometry Step by Step from the Land of the Incas"]
- The Butterfly Theorem at cut-the-knot
- A Better Butterfly Theorem at cut-the-knot
- Proof of Butterfly Theorem at PlanetMath
