The Butterfly Theorem

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Pakkinee Chitsakul


There are many methods for solving butterfly theorem. This paper derives the butterfly theorem by using the properties of similar triangles and theorem of intersecting chords. This technique is the simple one that can be used for solving some Euclidean geometry problems.

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How to Cite
Chitsakul, P. (2018). The Butterfly Theorem. Mathematical Journal by The Mathematical Association of Thailand Under The Patronage of His Majesty The King, 62(691), 13–20. Retrieved from
Academic Article


[1] Alexander Bogomolny. 2016. The Butterfly Theorem. Retrieved 22 November 2016 from

[2] Alexander Bogomolny. 2016. Intersecting Chord Theorem. Retrieved 3 December 2016 from

[3] H.S.M. Coxeter and S.L. Greitzer, Geometry Revisited, New York, 1967.