MathDB
ITAmo 2017, P4

Source: ITAmo 2017

May 5, 2017
geometry

Problem Statement

Let ABCDABCD be a thetraedron with the following propriety: the four lines connecting a vertex and the incenter of opposite face are concurrent. Prove AB⋅CD=AC⋅BD=AD⋅BCAB \cdot CD= AC \cdot BD = AD\cdot BC.
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