perimeter of the triangle DEF is two times larger than the side BC
Source: 2014 Oral Moscow Geometry Olympiad grades 8-9 p5
August 9, 2019
circumcirclegeometryperimeter
Problem Statement
Segment is the diameter of the circumscribed circle of an acute-angled triangle . Through the intersection of the altitudes of this triangle, a straight line was drawn parallel to the side , which intersects sides and at points and , respectively. Prove that the perimeter of the triangle is two times larger than the side .