MathDB
Medians and an identity

Source: Romanian District Olympiad 2014, Grade 9, P3

June 15, 2014
geometry proposedgeometry

Problem Statement

The medians AD,BEAD, BE and CFCF of triangle ABCABC intersect at GG. Let PP be a point lying in the interior of the triangle, not belonging to any of its medians. The line through PP parallel to ADAD intersects the side BCBC at A1A_{1}. Similarly one defines the points B1B_{1} and C1C_{1}. Prove that A1D+B1E+C1F=32PG \overline{A_{1}D}+\overline{B_{1}E}+\overline{C_{1}F}=\frac{3}{2}\overline{PG}