MathDB
RMO 2017 P1

Source: RMO 2017 P1

October 8, 2017
constructionsgeometry

Problem Statement

Let AOBAOB be a given angle less than 180180^{\circ} and let PP be an interior point of the angular region determined by AOB\angle AOB. Show, with proof, how to construct, using only ruler and compass, a line segment CDCD passing through PP such that CC lies on the way OAOA and DD lies on the ray OBOB, and CP:PD=1:2CP:PD=1:2.