both cyclic and tangential ABCD construction (3 points given)
Source: Sharygin 2006 finals 10.6
September 29, 2019
geometrycyclic quadrilateraltangential quadrilateralconstructionincenterCircumcenter
Problem Statement
A quadrangle was drawn on the board, that you can inscribe and circumscribe a circle. Marked are the centers of these circles and the intersection point of the lines connecting the midpoints of the opposite sides, after which the quadrangle itself was erased. Restore it with a compass and ruler.