MathDB
Putnam 1947 A3

Source: Putnam 1947

April 3, 2022
Putnamgeometrypolygonlines

Problem Statement

Given a triangle ABCABC with an interior point PP and points Q1,Q2Q_1 , Q_2 not lying on any of the segments AB,AC,BC,AB , AC ,BC, AP,BP,CP,AP ,BP ,CP, show that there does not exist a polygonal line KK joining Q1Q_1 and Q2Q_2 such that i) KK crosses each segment exactly once, ii) KK does not intersect itself iii) KK does not pass through A,B,CA, B , C or P.P.