MathDB

8 lines and incircle

Source: Sharygin final round 2017

July 31, 2017

geometry

Problem Statement

Given triangle

ABC

and its incircle

\omega

prove you can use just a ruler and drawing at most 8 lines to construct points

A',B',C'

\omega

such that

A,B',C'

and

B,C',A'

and

C,A',B'

are collinear.