No CrossRef data available.
Published online by Cambridge University Press: 01 August 2016
In an obituary of M. L. Urquhart in [1], David Elliott quotes him as claiming that Urquhart's theorem (below) is the most elementary theorem of Euclidean Geometry ‘since it involves only the concepts of straight line and distance’.
Urquhart's theorem
Let AC and AE be two straight lines.
Let B be a point on AC, D a point on AE, and suppose that BE and CD intersect at F.
If AB + BF = AD + DF then AC + CF = AE + EF. (1)