MathDB
Rhombus

Source: RMO 2004, Grade 7, Problem 1

February 26, 2006
geometryrhombusparallelogramvector

Problem Statement

On the sides AB,ADAB,AD of the rhombus ABCDABCD are the points E,FE,F such that AE=DFAE=DF. The lines BC,DEBC,DE intersect at PP and CD,BFCD,BF intersect at QQ. Prove that: (a) PEPD+QFQB=1\frac{PE}{PD} + \frac{QF}{QB} = 1; (b) P,A,QP,A,Q are collinear. Virginia Tica, Vasile Tica