IMO Shortlist 1996 problem G1
Kvaliteta:
Avg: 5,0Težina:
Avg: 5,0 Let
be a triangle, and
its orthocenter. Let
be a point on the circumcircle of triangle
(distinct from the vertices
,
,
), and let
be the foot of the altitude of triangle
from the vertex
. Let the parallel to the line
through the point
meet the parallel to the line
through the point
at a point
. Let the parallel to the line
through the point
meet the parallel to the line
through the point
at a point
. The lines
and
intersect at some point
. Prove that the lines
and
are parallel.
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Izvor: Međunarodna matematička olimpijada, shortlist 1996