On an inequality between side lengths of triangles

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Ruti Segal
Moshe Stupel

Abstract




The authors, using a proof without words style, explore a lesser known variation of the triangle inequality involving the difference between the sum of the lengths of any two sides and the length of the third side. The authors provide a web applet for further exploration.




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Author Biographies

Ruti Segal, Oranim – Academic College of Education, Tivon, Israel, and Shaanan, Academic College of Education, Haifa, Israel.

Ruti Segal is a Senior lecture of Mathematics Education at Oranim – Academic College of Education, Tivon, Israel, and Shaanan, Academic College of Education, Haifa, Israel. Department Chair M.Ed. in Mathematics and Science of Primary School Education. Her main research areas include (i) professional development of mathematics teachers and mathematics teacher educators, (ii) technology integration in mathematics learning and teaching, (iii) the development of math professional learning communi- ties and teachers community of practice, and (iv) integrating mathematics news snapshots in high-school mathematics lessons.

Moshe Stupel, Shaanan Academic Education College

Moshe Stupel is a Professor of Mathematics Education at Gordon - Academic College of Education, and Shaanan - Academic Col- lege of Education, Haifa, Israel. Dr. Stupel has extensive experience in the study of dynamic properties using computerized technology. He has published more than 200 articles in journals on technology and mathematics education, two books, and several mathematical enrichment materials. He also develops Geometric constructions and finds different solutions to the same problem by combining different mathematical tools.