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Bound sum of ratios of areas in triangle

Source: Bundeswettbewerb Mathematik 2024, Round 2 - Problem 3

September 13, 2024
ratiogeometrygeometry proposedarea of a triangleinequalities

Problem Statement

Let ABCABC be a triangle. For a point PP in its interior, we draw the threee lines through PP parallel to the sides of the triangle. This partitions ABCABC in three triangles and three quadrilaterals.
Let VAV_A be the area of the quadrilateral which has AA as one vertex. Let DAD_A be the area of the triangle which has a part of BCBC as one of its sides. Define VB,DBV_B, D_B and VC,DCV_C, D_C similarly.
Determine all possible values of DAVA+DBVB+DCVC\frac{D_A}{V_A}+\frac{D_B}{V_B}+\frac{D_C}{V_C}, as PP varies in the interior of the triangle.