Abstract
We show that if we start with an absolute plane, remove Side-Angle-Side as an axiom, and replace it with Side-Side-Side together with a weakened version of the triangle inequality as new axioms, then the new resulting axiom system is also an absolute plane. In particular, we show that Side-Angle-Side still holds in the new axiom system. In addition, we give a new proof of the two-circle theorem which does not depend on Side-Angle-Side, but instead uses Side-Side-Side and the weakened version of the triangle inequality.
Similar content being viewed by others
References
Birkhoff G.D.: A set of postulates for plane geometry based on scale and protractor. Ann. of Math. 33, 329–345 (1932)
Donnelly J.: The equivalence of Side-Angle-Side and Side-Angle-Angle in the absolute plane. J. Geom. 97, 69–82 (2010)
Borsuk, K., Szmielew, W.: Foundations of geometry, euclidean and Bolyai-Lobachevskian geometry, projective geometry. North-Holland, Amsterdam (1960)
Greenberg, M.J.: Euclidean and non-euclidean geometries: development and history. Freeman, New York (1993)
Hartshorne, R.: Geometry: Euclid and beyond. Springer, New York (2000)
Hilbert, D.: Grundlagen der geometrie. Teubner, Leipzig (1899)
Karzel, H., Sörensen, K., Windelberg, D.: Einf uhrung in die geometrie. Vandenhoeck and Ruprecht, Göttingen (1973)
Martin G.E.: The foundations of geometry and the non-euclidean plane. Springer, New York (1986)
Millman R., Parker G.: Geometry: a metric approach with models. Springer, New York (1991)
Moise, E.E.: Elementary geometry from an advanced standpoint. Addison-Wesley, Reading (1990)
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Donnelly, J. The equivalence of Side-Angle-Side with Side-Side-Side and the general triangle inequality in the absolute plane. J. Geom. 104, 265–275 (2013). https://doi.org/10.1007/s00022-013-0163-5
Received:
Revised:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s00022-013-0163-5