polygon, a line $l$ and a point $P$ on $l$
Source: ARMO 1997, 11.6
April 20, 2013
geometry proposedgeometry
Problem Statement
We are given a polygon, a line and a point on in general position: all lines containing a side of the polygon meet at distinct points diering from .
We mark each vertex of the polygon the sides meeting which, extended away from the vertex, meet the
line on opposite sides of . Show that lies inside the polygon if and only if on each side of there are an odd number of marked vertices.
O. Musin