Sangaku or San Gaku (算額; lit. mathematical tablet) are Japanese geometrical puzzles in Euclidean geometry on wooden tablets created during the Edo period (1603-1867) by members of all social classes.

During this period Japan was completely isolated from the rest of the world so the tablets were created using Japanese mathematics, (wasan), not influenced by western mathematical thought. For example, the fundamental connection between an integral and its derivative was unknown so Sangaku problems on areas and volumes were solved by expansions in infinite series and term-by-term calculation.

The Sangaku were painted in color on wooden tablets which were hung in the precincts of temples and shrines as offerings to the gods. Many of these tablets were lost following during the period of modernisation that followed the Edo period but around nine hundred are known to remain. The Sangaku were published for the first time in 1989 by Hidetoshi Fukagawa and Daniel Pedoe in the book Japanese Temple Geometry Problems.

See also

• Seki Takakazu (Kowa Seki)

Further reading

• Japanese Temple Geometry Problems: San Gaku. H. Fukagawa and D. Pedoe. (Charles Babbage Research Centre. 1989)

• "Japanese Temple Geometry," Tony Rothman with the cooperation of Hidetoshi Fugakawa, Scientific American, May 1998.

External links

• http://matcmadison.edu/is/as/math/kmirus/Reference/SanGaku.html
• Sangaku problem by Antonio Gutierrez from "Geometry Step by Step from the Land of the Incas"
• http://www.sangaku.info/
• http://www.wasan.jp/english/
• http://www.loyola.edu/maru/sangaku.html
• http://www2.gol.com/users/coynerhm/0598rothman.html
• Pythagoras and Vecten Break Japan's Isolation

Japanese games | Euclidean geometry | Recreational mathematics | Science and technology in Japan

Sangaku | 算額