MathDB
Locus

Source: Iran 2005

August 27, 2005
geometryrectanglegeometry proposed

Problem Statement

From each vertex of triangle ABCABC we draw 3 arbitary parrallell lines, and from each vertex we draw a perpendicular to these lines. There are 3 rectangles that one of their diagnals is triangle's side. We draw their other diagnals and call them 1\ell_1, 2\ell_2 and 3\ell_3. a) Prove that 1\ell_1, 2\ell_2 and 3\ell_3 are concurrent at a point PP. b) Find the locus of PP as we move the 3 arbitary lines.