MathDB

Let

ABC

be a triangle and

ABDE, BCFZ, CAKL

be three similar rectangles constructed externally of the triangle. Let

A'

be the intersection of

EF

and

ZK, B'

the intersection of

KZ

and

DL

, and

C'

the intersection of

DL

and

EF

. Prove that

AA'

passes through the midpoint of the line segment

B'C'

.
Kostas Vittas

Problem Statement