Abstract
The expression C = π D, which gives the relationship between the circumference C and the diameter D of a circle, is one of the few formulas known to almost all children and adults, regardless of how long they have been out of school. School-going children are introduced to this relation in their 7th grade. How this is done in India is illustrated by a snapshot from a textbook (NCERT, Mathematics, Grade 7, Chapter 11, [1].)
There is no reference as to who proved it first, leave aside any proof of this fact. More so at no stage in the school curriculum, there is a reference to a proof of this for self-study. The aim of this article is to provide arguments that are rigorous and accessible to upper middle-grade students to illustrate the fact that C/D is constant for every circle.
References
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Acknowledgement
• Part of this note was prepared during my engagement as an Adjunct Faculty at SGT University, Gurugram. I would like to thank the authorities at SGT University for the opportunity.
• I would like to thank the referee for the corrections and suggestions in preparing this note.
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Inder K. Rana is retired from IIT Bombay as Emeritus Fellow in June 2022.
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Rana, I.K. Making π Accessible. Reson 28, 1075–1091 (2023). https://doi.org/10.1007/s12045-023-1638-9
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DOI: https://doi.org/10.1007/s12045-023-1638-9