SEMI-CIRCLES, ELLIPSES AND SUPER ELLIPSES DISTINGUISHED BY INSCRIBED RIGHT ANGLE
Keywords:
Thales’ theorem, inscribed right angle, semi circle, semi-ellipse, semi- super ellipseDOI:
https://doi.org/10.17654/0973563125018Abstract
Thales’ theorem says that the angle subtended by the base at any point of the upper half of a circle is a right angle. We derive a formula that proves Thales’ theorem and its converse, and apply it to seek points on the upper half an ellipse and more generally on the upper half of a super ellipse, where the angle subtended by the base diameter makes a right angle. Our results show a way of distinguishing among a semi-circle, ellipse and super ellipse. The contents of this paper can be understood by undergraduate students with calculus background.
Received: October 1, 2025
Accepted: November 1, 2025
References
[1] S. Ceribasi and G. Altay, Free vibration of super elliptical plates with constant and variable thickness by Ritz method, J. Sound. Vib. 319 (2009), 668-680.
[2] N. T. Gridgeman, Lamé ovals, The Math. Gazette 54 (387) (1970), 31-37.
[3] Thomas L. Heath, The Thirteen Books of Euclid’s Elements, Vol. 2 (Books 3-9), 2nd ed., Dover, 1956, p. 61, Originally published by Cambridge University Press, 2nd ed., 1926.
[4] T. Patronis and D. Patsopoulos, The theorem of Thales: a study of the naming of theorems in school geometry textbooks, The International Journal for the History of Mathematics Education 1 (2006), 57-68.
[5] R. D. Poodiack, Squigonometry, hyperellipses and supereggs, Math. Mag. 89(2) (2016), 92-100.
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