Sangaku Journal of Mathematics
Published by the Association for the Development of Education, Sofia, Bulgaria
About this Journal
 Editorial Board
 Instructions for Authors
 Review Process
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ISSN 25349562
Editorsin Chief:
Hiroshi Okumura, Professor, Ph.D.
Takahanadai Maebashi Gunma, Japan
email: hokmr@yandex.com
Sava Grozdev, Professor, DSc,
Association for the Development of Education, Sofia, Bulgaria
email: sava.grozdev@gmail.com
Volume 8 (2024)
Volume 7 (2023)

Hiroshi Okumura,
A rare sangaku problem involving three congruent circles, pp.18.


Hiroshi Okumura,
Problems 20231, pp.912.


Paris Pamfilos,
Note on a sangaku like construction of X(55), pp. 1315.


Vishwesh Ravi Shrimali,
Solution for Problems 2 and 3 of Problems 20231, pp. 1619.


Kousik Sett,
Solution for Problems 2 and 3 of Problems 20231 by Vishwesh Ravi Shrimali (ERRATA), p. 20.


Ercole Suppa and Marian Cucoanes,
Solution of Problems 202316, pp. 2128.


Hiroshi Okumura and Kousik Sett,
The arbelos in Wasan geometry: the Aida arbelos and Problem 202315, pp. 2931.


Hiroshi Okumura,
A configuration arising from Problem 202311, pp. 3234.


KaiUwe Ekrutt and Floor van Lamoen,
Further notes on Tamura’s problem in the general arbelos, pp. 3541.


Paris Pamfilos,
On a sangaku like configuration involving a triangle and three congruent circles, pp. 4253.


Ercole Suppa and Stanley Rabinowitz,
A triad of circles associated with a triangle, pp. 5470.


Stanley Rabinowitz and Ercole Suppa,
Properties of Ajima circles, pp. 71145.


Hiroshi Okumura and Dao Thanh Oai,
Twin circles of a generalized arbelos with division by zero 1/0=0, pp. 146150.


Kousik Sett,
Relationships between radii in a sixcircle configuration, pp. 151161.

Volume 6 (2022)

Hiroshi Okumura,
A note on a generalization of a five circle problem, pp.12.


Hiroshi Okumura,
A note on a generalization of a five circle problem: Part 2, pp.35.


Hiroshi Okumura,
A note on a generalization of a five circle problem: Part 3, pp.68.


Li Ting Hon Stanford,
A configuration involving a square and two equilateral triangles, pp.912.


Hiroshi Okumura,
Some generalizations of five circle problems, pp.1318.


Hiroshi Okumura,
A note on circles touching two circles in a Pappus chain, pp.1922.


Hiroshi Okumura,
A note on circles touching two circles in a Pappus chain: Part 2, pp.2325.


Kousik Sett,
A note on a chain of contact circles inside a circular segment, pp.2630.


Kousik Sett,
An alternative proof of the Japanese theorem, pp.3133.


Li Ting Hon Stanford,
A simple method to explore the relationships between six areas, pp.3436.


Hiroshi Okumura,
A note on circles touching two circles in a Pappus chain: Part 3, pp.3740.


J. Marshall Unger,
A response to an open question of Rabinowitz, pp.4144.

Volume 5 (2021)

Hiroshi Okumura,
The arbelos in Wasan geometry, the inscribed semicircle in the arbelos, pp.18.


Li Ting Hon Stanford,
Ellipses inscribed in trapezoids and solutions to 20201 Problems 1 and 2, pp.913.


Hiroshi Okumura,
The arbelos in Wasan geometry: Totsuka's problem (Problem 201736), pp.1418.


Kousik Sett,
A constant associated with Ikeda's theorem, pp.1923.


Hiroshi Okumura,
The arbelos in Wasan geometry: Saitoh's problem, pp.2431.


Hiroshi Okumura,
The arbelos in Wasan geometry: Atsumi's problem with division by zero calculus, pp.3238.


Hiroshi Okumura,
The arbelos in Wasan geometry: a problem in Sangaku Shōsen, pp.3942.


J. Marshall Unger,
How Wasanka did integration: The case of the Japanese wedge, pp.4355.

Volume 4 (2020)

Hiroshi Okumura,
A four circle problem and division by zero, pp.18.


Stanley Rabinowitz,
Relationships between circles inscribed in triangles and related curvilinear triangles, pp.927.


Hiroshi Okumura and Ercole Suppa,
A remark on an Archimedean square of a triangle associated with an arbelos, pp.2830.


Hiroshi Okumura,
Ootoba's Archimedean circles of the collinear arbelos, pp.3135.


Problems 20201, pp.3640.


Géry Huvent, Solution to Problem 20194, pp.4144.


Hiroshi Okumura, A generalization of Problem 20194 and division by zero, pp.4552.


Géry Huvent, Solution to Problem 20201 Problem 9, pp.5360.


Hiroshi Okumura, NonArchimedean congruent circles in Tenzan Tebikigusa Furoku, pp.6168.


Abdilkadir Altintas, Problem 20202, p.69.


Kousik Sett, Solution to Problem 20202, pp.7072.


Hiroshi Okumura, Solution to Problem 201716 with division by zero, pp.7376.


Stanley Rabinowitz, Relationships between six areas, pp.7783.
Supplementary Material. sixAreas.nb


Li Ting Hon Stanford, A note on a sangaku problem involving the Steiner ellipse, pp.8485.


Emmanuel Antonio Jose Garcia, Three Archimedean circles arising from equilateral triangles, pp.8687.

Volume 3 (2019)

Le Viet An and Emmanuel Antonio Jose Garcia,
A pair of Archimedean incircles, pp.12.


Paul Yiu and XiaoDong Zhang,
Diagram 29 in the appendix of Yojutsu Shindai, pp.311.


Hiroshi Okumura,
A note on the arbelos in Wasan geometry, a
problem in Sampo Tenzan Tebikigusa Furoku, pp.1214.


Hiroshi Okumura,
A note on the arbelos in Wasan geometry,
Satoh’s problem, pp.1516.


Problems 20191, pp.1718.


Hiroshi Okumura,
A note on the arbelos in Wasan geometry, Matsuda’s problem, pp.1923.


Hiroshi Okumura, Problems 20192, pp.2425.


Problems 20193, pp.2628.


Kyouichi Gowa and Chieko Miyota,
A sangaku problem involving four circles in a
rectangle, pp.2931.


Waldemar Pompe,
On a sangaku problem involving the incircles in
a square tiling: Solutions to Problems 20192, pp.3235.


Tsutomu Matsuura, Hiroshi Okumura, and Saburou Saitoh,
Division by zero calculus and Pompe's theorem, pp.3640.


Hiroshi Okumura,
Arbeloi determined by a chord and solutions to Problems 201738 and 201934, pp.4150.


Stanley Rabinowitz,
Relationships between six incircles, pp.5166.
Supplementary Material. Sixincircles.zip


Hiroshi Okumura,
A characterization of the golden arbelos involving an Archimedean circle, pp.6771.


Problems 20194, pp.7272.


Stanley Rabinowitz,
Relationships between six excircles, pp.7390.
Supplementary Material. Sixexcircles.zip


Hiroshi Okumura,
The arbelos in Wasan geometry: Ootoba's problem and Archimedean circles, pp.9197.


Stanley Rabinowitz,
Relationships between six circumcircles, pp.98105.


Stanley Rabinowitz,
More relationships between six circles, pp.106118.


Hiroshi Okumura,
Remarks on Archimedean circles of Nagata and Ootoba, pp.119122.


Hiroshi Okumura,
Remarks on a problem involving four circles in a parallelogram, pp.123125.

Volume 2 (2018)

Giovanni Lucca,
A note on a Pappus sangaku problem
and a Family of Integer Sequences, pp.12.


Hiroshi Okumura,
A note on a problem involving a square in a curvilinear triangle, pp.35.


Problems 20181, p.6.


Abdilkadir Altintas,
Problems 20182, p.7.


Hiroshi Okumura,
A note on an isosceles triangle containing a square and three congruent circles, pp.810.


Abdilkadir Altintas and Hiroshi Okumura,
A note on Pappus chain and a collinear theorem, pp. 1112.


Viera Čerňanová,
Solution to 20181 Problem 2, pp.1314.


Viera Čerňanová,
Solution to 20181 Problem 1, pp.1516.


Hiroshi Okumura,
Solution to 20173 Problem 5, pp.1721.


Jana Fialová,
Solution to 20182 Problem 1, pp.2223.


Hiroshi Okumura,
Solution to the problem proposed in "Solution to 20173 Problem 5", pp.2426.


Hiroshi Okumura,
Solution to 20171 Problem 4 with division by zero, pp.2730.


Giovanni Lucca,
Integer sequences and circle chains inside a tangential quadrilateral, pp.3140.


Problems 20183, pp.4142.


Hiroshi Kinoshita,
An unsolved problem in the Yamaguchi's travell diary, pp.4353.
The paper is reprinted from "Shotoh Sugaku",
Volume 70 (2012) pp. 3236 with permission from the publisher
along with a supplementary Appendix.


Hiroshi Okumura,
Solution to Problem 201832, pp.5456.


Hiroshi Okumura and Saburou Saitoh,
Wasan Geometry and Division by Zero Calculus, pp.5773.


Li Ting Hon Stanford,
Solution to 20173 Problem 3, pp.7475.


Jana Fialová,
Inscribed rectangles in a kite and a solution to
20171 Problem 5, pp.7682.

Volume 1 (2017)

Hiroshi Okumura, Japanese mathematics, pp.16.
The paper is reprinted from "Symmetry: Culture and Science",Volume 12
(12) 7986 (2001) with permission from the publisher.


Problems 20171, pp.710.


Problems 20172, pp.1112.


Francisco Javier García Capitán,
Solution to 20171 Problem 1, pp.1315.


Yasuo Kanai and Hiroshi Okumura,
A three tangent congruent circle problem, pp.1620.
Supplementary material: animation.gif


Problems 20173, pp.2123.


Hiroshi Okumura,
Configurations of congruent circles on a line, pp.2434.


Hiroshi Okumura,
Theorems on two congruent circles on a line, pp.3538.


Hiroshi Okumura,
A note on the problems involving congruent circles in Tenzan Kaitei, pp.3941.


Hiroshi Okumura,
Haga's theorems in paper folding and related theorems in Wasan geometry Part 1, pp.4256.

