perpendicular diagonals criterion for a cyclic quadrilateral
Source: Sharygin 2005 Finals 9.1
August 26, 2019
cyclic quadrilateralequal anglesperpendiculardiagonalsgeometry
Problem Statement
The quadrangle is inscribed in a circle whose center lies inside it.
Prove that if , then the diagonals of the quadrilateral are perpendicular.