Generalizing a property of isosceles trapezoids in the real plane into real normed spaces, a couple of characterizations of inner product spaces (i.p.s) are obtained.
@article{107682, author = {Claudi Alsina and P. Cruells and M. S. Tom\'as}, title = {Characterizations of inner product spaces through an isosceles trapezoid property}, journal = {Archivum Mathematicum}, volume = {035}, year = {1999}, pages = {21-27}, zbl = {1050.46507}, mrnumber = {1684520}, language = {en}, url = {http://dml.mathdoc.fr/item/107682} }
Alsina, Claudi; Cruells, P.; Tomás, M. S. Characterizations of inner product spaces through an isosceles trapezoid property. Archivum Mathematicum, Tome 035 (1999) pp. 21-27. http://gdmltest.u-ga.fr/item/107682/
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