Maria Flavia Mammana, Biagio Micale, and Mario Pennisi,
Properties of valtitudes and vaxes of a convex quadrilateral,
Forum Geometricorum, 12 (2012) 47--61.

Abstract.   We introduce the vaxes relative to a v-parallelogram and determine several properties of valtitudes and of vaxes. In particular, we study the quadrilateral detected by the valtitudes and the one detected by the vaxes.

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