MathDB
unusual distance <15 problem, each side <20 in quadr. 1988 Kyiv City MO 9.1

Source:

July 16, 2021
geometrygeometric inequality

Problem Statement

Each side of a convex quadrilateral is less than 2020 cm. Prove that you can specify the vertex of the quadrilateral, the distance from which to any point QQ inside the quadrilateral is less than 1515 cm.