19 lines in the plane dividing the plane into exactly 9$ pieces
Source: 1997 Estonia National Olympiad Final Round grade 12 p4
March 11, 2020
combinatoricslinescombinatorial geometry
Problem Statement
There are lines in the plane dividing the plane into exactly pieces.
(a) Prove that among these pieces there is at least one triangle.
(b) Show that it is indeed possible to place lines in the above way.