MathDB

ASU 305 All Soviet Union MO 1981 perpendicular chords inside a cyclic

Source:

July 23, 2019

parallelperpendicularCyclic

Problem Statement

Given points

A,B,M,N

on the circumference. Two chords

[MA_1]

and

[MA_2]

are orthogonal to lines

(NA)

and

(NB)

respectively. Prove that

(AA_1)

and

(BB_1)

lines are parallel.