Y by
Let
be an acute triangle inscribed in a circle
and let
be the midpoints of segment
, of segment
and minor arc
of
, respectively. Let
and
be points in
such that
and that
.
a) Prove how that the line joining the centers of the circumscribed circles of the triangles
and
, is parallel to
.
b) If
and
intersect at
, and
and
intersect at
, prove that
is parallel to
.












a) Prove how that the line joining the centers of the circumscribed circles of the triangles



b) If







