MathDB
Parallelism

Source: 2013 Baltic Way, Problem 14

December 31, 2013
geometrygeometric transformationhomothetyparallelogramangle bisectorgeometry unsolved

Problem Statement

Circles α\alpha and β\beta of the same radius intersect in two points, one of which is PP. Denote by AA and BB, respectively, the points diametrically opposite to PP on each of α\alpha and β\beta . A third circle of the same radius passes through PP and intersects α\alpha and β\beta in the points XX and YY , respectively. Show that the line XYXY is parallel to the line ABAB.