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Triangles and Reuleaux triangles in Banach-Minkowski planes. (English) Zbl 0824.51016

Böröczky, K. (ed.) et al., Intuitive geometry. Proceedings of the 3rd international conference held in Szeged, Hungary, from 2 to 7 September, 1991. Amsterdam: North-Holland. Colloq. Math. Soc. János Bolyai. 63, 505-511 (1994).
In the present paper previously established results on the area of equilateral triangles with side length 1 in Banach-Minkowski planes [H. Reimann, Wiss. Z. PH Erfurt/Mühlhausen 23, No. 1, 124-132 (1987; Zbl 0627.52006) and M. Wellmann and the author, Wiss. Z. PH Erfurt/Mühlhausen 27, No. 1, 21-28 (1991; Zbl 0753.52001)] are transferred to obtain theorems on the area of Releaux triangles with width 1. For example, the Minkowski area of such a Releaux triangle always lies in the interval \([\pi/6, \pi/4]\). It is equal to \(\pi/6\) if and only if the gauge figure (indicatrix) is an affinely regular hexagon. It is equal to \(\pi/4\) if and only if the gauge figure is a parallelogram. In addition it turns out that the gauge figure is completely determined by one Releaux triangle.
For the entire collection see [Zbl 0809.00022].
Reviewer: H.Havlicek (Wien)

MSC:

51M20 Polyhedra and polytopes; regular figures, division of spaces
52A10 Convex sets in \(2\) dimensions (including convex curves)