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Secant less than half trapezoid perimeter

Source: Iranian Geometry Olympiad 2016 Medium 1

May 26, 2017
geometrytrapezoidperimeter

Problem Statement

In trapezoid ABCDABCD with ABCDAB || CD, ω1\omega_1 and ω2\omega_2 are two circles with diameters ADAD and BCBC, respectively. Let XX and YY be two arbitrary points on ω1\omega_1 and ω2\omega_2, respectively. Show that the length of segment XYXY is not more than half the perimeter of ABCDABCD.
Proposed by Mahdi Etesami Fard