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The Compleat Ceva

Published online by Cambridge University Press:  01 August 2016

G. C. Shephard*
Affiliation:
School of Mathematics, University of East Anglia, Norwich NR4 7TJ, email: g.shephard@uea.ac.uk

Extract

1. Ceva’s Theorem (Figure 1) is a familiar result in elementary geometry. It states that the product of three ratios of line segments on the sides of a triangle takes the fixed value 1. An n-gonal form of the theorem is also known, and this is just one of a large class of results concerning cyclic products of ratios of line segments on the sides or diagonals of an n-gon. In particular, suppose M is a fixed point (the Ceva point) and P = [V0, … , Vn-1] is an n-gon. Consider the lines MVi, joining the Ceva point to each of the vertices of P. These lines will cut the sides and diagonals of P in certain ratios, and each cyclic product of such ratios either takes a constant value or is related to another such cyclic product in a simple manner. The purpose of this note is to determine all such relations.

Type
Articles
Copyright
Copyright © The Mathematical Association 1999

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References

1. Grünbaum, Branko and Shephard, G.C., Ceva, Menelaus, and the area principle. Mathematics Magazine 68 (1995) pp. 254268.CrossRefGoogle Scholar
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