parallel angle bisectors to the angle bisectors of diagonals in a cyclic ABCD
Source: 2018 (-19) Swedish Mathematical Competition p1
August 10, 2020
geometryangle bisectorparallelcyclic quadrilateral
Problem Statement
Let the be a quadrilateral without parallel sides, inscribed in a circle. Let and be the intersection points between the lines containing the quadrilateral opposite sides. Show that the bisectors to the angles at and are parallel to the bisectors of the angles at the intersection point of the diagonals of the quadrilateral.