Sangaku Journal of Mathematics
Published by the Association for the Development of Education, Sofia, Bulgaria
About this Journal
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ISSN 2534-9562
Editors-in Chief:
Hiroshi Okumura, Professor, Ph.D.
Takahanadai Maebashi Gunma, Japan
e-mail: hokmr@yandex.com
Sava Grozdev, Professor, DSc,
Association for the Development of Education, Sofia, Bulgaria
e-mail: sava.grozdev@gmail.com
Volume 8 (2024)
Volume 7 (2023)
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Hiroshi Okumura,
A rare sangaku problem involving three congruent circles, pp.1-8.
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Hiroshi Okumura,
Problems 2023-1, pp.9-12.
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Paris Pamfilos,
Note on a sangaku like construction of X(55), pp. 13-15.
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Vishwesh Ravi Shrimali,
Solution for Problems 2 and 3 of Problems 2023-1, pp. 16-19.
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Kousik Sett,
Solution for Problems 2 and 3 of Problems 2023-1 by Vishwesh Ravi Shrimali (ERRATA), p. 20.
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Ercole Suppa and Marian Cucoanes,
Solution of Problems 2023-1-6, pp. 21-28.
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Hiroshi Okumura and Kousik Sett,
The arbelos in Wasan geometry: the Aida arbelos and Problem 2023-1-5, pp. 29-31.
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Hiroshi Okumura,
A configuration arising from Problem 2023-1-1, pp. 32-34.
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Kai-Uwe Ekrutt and Floor van Lamoen,
Further notes on Tamura’s problem in the general arbelos, pp. 35-41.
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Paris Pamfilos,
On a sangaku like configuration involving a triangle and three congruent circles, pp. 42-53.
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Ercole Suppa and Stanley Rabinowitz,
A triad of circles associated with a triangle, pp. 54-70.
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Stanley Rabinowitz and Ercole Suppa,
Properties of Ajima circles, pp. 71-145.
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Hiroshi Okumura and Dao Thanh Oai,
Twin circles of a generalized arbelos with division by zero 1/0=0, pp. 146-150.
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Kousik Sett,
Relationships between radii in a six-circle configuration, pp. 151-161.
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Volume 6 (2022)
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Hiroshi Okumura,
A note on a generalization of a five circle problem, pp.1-2.
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Hiroshi Okumura,
A note on a generalization of a five circle problem: Part 2, pp.3-5.
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Hiroshi Okumura,
A note on a generalization of a five circle problem: Part 3, pp.6-8.
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Li Ting Hon Stanford,
A configuration involving a square and two equilateral triangles, pp.9-12.
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Hiroshi Okumura,
Some generalizations of five circle problems, pp.13-18.
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Hiroshi Okumura,
A note on circles touching two circles in a Pappus chain, pp.19-22.
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Hiroshi Okumura,
A note on circles touching two circles in a Pappus chain: Part 2, pp.23-25.
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Kousik Sett,
A note on a chain of contact circles inside a circular segment, pp.26-30.
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Kousik Sett,
An alternative proof of the Japanese theorem, pp.31-33.
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Li Ting Hon Stanford,
A simple method to explore the relationships between six areas, pp.34-36.
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Hiroshi Okumura,
A note on circles touching two circles in a Pappus chain: Part 3, pp.37-40.
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J. Marshall Unger,
A response to an open question of Rabinowitz, pp.41-44.
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Volume 5 (2021)
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Hiroshi Okumura,
The arbelos in Wasan geometry, the inscribed semicircle in the arbelos, pp.1-8.
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Li Ting Hon Stanford,
Ellipses inscribed in trapezoids and solutions to 2020-1 Problems 1 and 2, pp.9-13.
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Hiroshi Okumura,
The arbelos in Wasan geometry: Totsuka's problem (Problem 2017-3-6), pp.14-18.
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Kousik Sett,
A constant associated with Ikeda's theorem, pp.19-23.
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Hiroshi Okumura,
The arbelos in Wasan geometry: Saitoh's problem, pp.24-31.
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Hiroshi Okumura,
The arbelos in Wasan geometry: Atsumi's problem with division by zero calculus, pp.32-38.
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Hiroshi Okumura,
The arbelos in Wasan geometry: a problem in Sangaku Shōsen, pp.39-42.
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J. Marshall Unger,
How Wasanka did integration: The case of the Japanese wedge, pp.43-55.
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Volume 4 (2020)
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Hiroshi Okumura,
A four circle problem and division by zero, pp.1-8.
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Stanley Rabinowitz,
Relationships between circles inscribed in triangles and related curvilinear triangles, pp.9-27.
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Hiroshi Okumura and Ercole Suppa,
A remark on an Archimedean square of a triangle associated with an arbelos, pp.28-30.
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Hiroshi Okumura,
Ootoba's Archimedean circles of the collinear arbelos, pp.31-35.
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Problems 2020-1, pp.36-40.
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Géry Huvent, Solution to Problem 2019-4, pp.41-44.
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Hiroshi Okumura, A generalization of Problem 2019-4 and division by zero, pp.45-52.
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Géry Huvent, Solution to Problem 2020-1 Problem 9, pp.53-60.
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Hiroshi Okumura, Non-Archimedean congruent circles in Tenzan Tebikigusa Furoku, pp.61-68.
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Abdilkadir Altintas, Problem 2020-2, p.69.
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Kousik Sett, Solution to Problem 2020-2, pp.70-72.
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Hiroshi Okumura, Solution to Problem 2017-1-6 with division by zero, pp.73-76.
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Stanley Rabinowitz, Relationships between six areas, pp.77-83.
Supplementary Material. sixAreas.nb
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Li Ting Hon Stanford, A note on a sangaku problem involving the Steiner ellipse, pp.84-85.
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Emmanuel Antonio Jose Garcia, Three Archimedean circles arising from equilateral triangles, pp.86-87.
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Volume 3 (2019)
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Le Viet An and Emmanuel Antonio Jose Garcia,
A pair of Archimedean incircles, pp.1-2.
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Paul Yiu and Xiao-Dong Zhang,
Diagram 29 in the appendix of Yojutsu Shindai, pp.3-11.
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Hiroshi Okumura,
A note on the arbelos in Wasan geometry, a
problem in Sampo Tenzan Tebikigusa Furoku, pp.12-14.
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Hiroshi Okumura,
A note on the arbelos in Wasan geometry,
Satoh’s problem, pp.15-16.
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Problems 2019-1, pp.17-18.
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Hiroshi Okumura,
A note on the arbelos in Wasan geometry, Matsuda’s problem, pp.19-23.
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Hiroshi Okumura, Problems 2019-2, pp.24-25.
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Problems 2019-3, pp.26-28.
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Kyouichi Gowa and Chieko Miyota,
A sangaku problem involving four circles in a
rectangle, pp.29-31.
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Waldemar Pompe,
On a sangaku problem involving the incircles in
a square tiling: Solutions to Problems 2019-2, pp.32-35.
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Tsutomu Matsuura, Hiroshi Okumura, and Saburou Saitoh,
Division by zero calculus and Pompe's theorem, pp.36-40.
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Hiroshi Okumura,
Arbeloi determined by a chord and solutions to Problems 2017-3-8 and 2019-3-4, pp.41-50.
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Stanley Rabinowitz,
Relationships between six incircles, pp.51-66.
Supplementary Material. Sixincircles.zip
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Hiroshi Okumura,
A characterization of the golden arbelos involving an Archimedean circle, pp.67-71.
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Problems 2019-4, pp.72-72.
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Stanley Rabinowitz,
Relationships between six excircles, pp.73-90.
Supplementary Material. Sixexcircles.zip
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Hiroshi Okumura,
The arbelos in Wasan geometry: Ootoba's problem and Archimedean circles, pp.91-97.
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Stanley Rabinowitz,
Relationships between six circumcircles, pp.98-105.
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Stanley Rabinowitz,
More relationships between six circles, pp.106-118.
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Hiroshi Okumura,
Remarks on Archimedean circles of Nagata and Ootoba, pp.119-122.
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Hiroshi Okumura,
Remarks on a problem involving four circles in a parallelogram, pp.123-125.
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Volume 2 (2018)
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Giovanni Lucca,
A note on a Pappus sangaku problem
and a Family of Integer Sequences, pp.1-2.
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Hiroshi Okumura,
A note on a problem involving a square in a curvilinear triangle, pp.3-5.
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Problems 2018-1, p.6.
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Abdilkadir Altintas,
Problems 2018-2, p.7.
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Hiroshi Okumura,
A note on an isosceles triangle containing a square and three congruent circles, pp.8-10.
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Abdilkadir Altintas and Hiroshi Okumura,
A note on Pappus chain and a collinear theorem, pp. 11-12.
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Viera Čerňanová,
Solution to 2018-1 Problem 2, pp.13-14.
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Viera Čerňanová,
Solution to 2018-1 Problem 1, pp.15-16.
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Hiroshi Okumura,
Solution to 2017-3 Problem 5, pp.17-21.
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Jana Fialová,
Solution to 2018-2 Problem 1, pp.22-23.
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Hiroshi Okumura,
Solution to the problem proposed in "Solution to 2017-3 Problem 5", pp.24-26.
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Hiroshi Okumura,
Solution to 2017-1 Problem 4 with division by zero, pp.27-30.
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Giovanni Lucca,
Integer sequences and circle chains inside a tangential quadrilateral, pp.31-40.
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Problems 2018-3, pp.41-42.
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Hiroshi Kinoshita,
An unsolved problem in the Yamaguchi's travell diary, pp.43-53.
The paper is reprinted from "Shotoh Sugaku",
Volume 70 (2012) pp. 32-36 with permission from the publisher
along with a supplementary Appendix.
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Hiroshi Okumura,
Solution to Problem 2018-3-2, pp.54-56.
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Hiroshi Okumura and Saburou Saitoh,
Wasan Geometry and Division by Zero Calculus, pp.57-73.
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Li Ting Hon Stanford,
Solution to 2017-3 Problem 3, pp.74-75.
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Jana Fialová,
Inscribed rectangles in a kite and a solution to
2017-1 Problem 5, pp.76-82.
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Volume 1 (2017)
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Hiroshi Okumura, Japanese mathematics, pp.1-6.
The paper is reprinted from "Symmetry: Culture and Science",Volume 12
(1-2) 79-86 (2001) with permission from the publisher.
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Problems 2017-1, pp.7-10.
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Problems 2017-2, pp.11-12.
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Francisco Javier García Capitán,
Solution to 2017-1 Problem 1, pp.13-15.
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Yasuo Kanai and Hiroshi Okumura,
A three tangent congruent circle problem, pp.16-20.
Supplementary material: animation.gif
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Problems 2017-3, pp.21-23.
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Hiroshi Okumura,
Configurations of congruent circles on a line, pp.24-34.
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Hiroshi Okumura,
Theorems on two congruent circles on a line, pp.35-38.
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Hiroshi Okumura,
A note on the problems involving congruent circles in Tenzan Kaitei, pp.39-41.
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Hiroshi Okumura,
Haga's theorems in paper folding and related theorems in Wasan geometry Part 1, pp.42-56.
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