MathDB
trapezium with one base double of the other, 4 perpendiculars, collinear wanted

Source: 1st Rioplatense Olympiad 1990 level 3 P3

September 4, 2018
geometrytrapezoidcollinearperpendicular

Problem Statement

Let ABCDABCD be a trapezium with bases ABAB and CDCD such that AB=2CDAB = 2 CD. From AA the line rr is drawn perpendicular to BCBC and from BB the line tt is drawn perpendicular to ADAD. Let PP be the intersection point of rr and tt. From CC the line ss is drawn perpendicular to BCBC and from DD the line uu perpendicular to ADAD. Let QQ be the intersection point of ss and uu. If RR is the intersection point of the diagonals of the trapezium, prove that points P,QP, Q and RR are collinear.