Sangaku Japanese Geometry Problems

Sangaku Problems - Table of Content

Problem 525.
Sangaku Japanese Geometry, Circles, Diameter, Tangent, Radius,
Congruence, Measurement.

Problem 524.
Sangaku Japanese Geometry, Circle, Equilateral Triangles, Midpoint, Side, Measurement.

Problem 336.
Two equal circles, a Common Tangent and a Square, Sangaku Japanese Geometry.

Sangaku Problem 41.
"Mickey Mouse." Three circles, tangents, radii.

Sangaku Three circles and a tangent line.

Sangaku Geometry Theorem: Cyclic Quadrilateral
Inradii, Rectangle.

Sangaku Problem (An Old Japanese Theorem)
Inradii, Carnot's theorem.

Puzzle: Sangaku Problem

Reference: Fukagawa Hidetoshi, Tony Rothman, "Sacred Mathematics: Japanese Temple Geometry" (Princenton University Press, 2008).
Between the seventeenth and nineteenth centuries Japan was totally isolated from the West by imperial decree. During that time, a unique brand of homegrown mathematics flourished, one that was completely uninfluenced by developments in Western mathematics. People from all walks of life—samurai, farmers, and merchants—inscribed a wide variety of geometry problems on wooden tablets called sangaku and hung them in Buddhist temples and Shinto shrines throughout Japan.