MathDB
HMMT Team 2019/1: Affine geometry

Source:

February 17, 2019
HMMTgeometryanalytic geometry

Problem Statement

Let ABCDABCD be a parallelogram. Points XX and YY lie on segments ABAB and ADAD respectively, and ACAC intersects XYXY at point ZZ. Prove that ABAX+ADAY=ACAZ.\frac{AB}{AX} + \frac{AD}{AY} = \frac{AC}{AZ}.