×

Three points related to the incenter and excenters of a triangle. (English) Zbl 1151.51301

Summary: The incenter and the three excenters of a triangle \(\triangle\) are the centers of those four circles touching every side of \(\triangle\). From these points three other points can be derived. The resulting triangle \(\triangle_S\) is produced from the triangle \(\triangle_A\) of the excenters by a \(180^\circ\) rotation around the Feuerbach point of \(\triangle\). The triangles \(\triangle_A\) and \(\triangle_S\) share the Euler line and the Feuerbach nine-point circle. The author uses elementary means to prove these and other results connected with them.

MSC:

51M04 Elementary problems in Euclidean geometries
Full Text: DOI

References:

[1] Coxeter, H.S.M.: Introduction to Geometry . J. Wiley & Sons, New York-London 1961. · Zbl 0095.34502
[2] Kimberling, C.: Encyclopedia of Triangle Centers. Available at http://faculty.evansville.edu/ck6/encyclopedia/ETC.html · Zbl 0803.51017
[3] Schwarz, H.A.: Gesammelte mathematische Abhandlungen . Springer, Berlin 1890. · JFM 22.0031.04
[4] Steiner, J.: Jacob Steiner’s Gesammelte Werke . (2 Bände) Reimer, Berlin 1881.
This reference list is based on information provided by the publisher or from digital mathematics libraries. Its items are heuristically matched to zbMATH identifiers and may contain data conversion errors. In some cases that data have been complemented/enhanced by data from zbMATH Open. This attempts to reflect the references listed in the original paper as accurately as possible without claiming completeness or a perfect matching.