Let
be an acute-angled triangle with orthocenter
, and let
be a point on side
. Denote by
and
the feet of the altitudes from
and
, respectively. Denote by
the circumcircle of
, and let
be the point on
which is diametrically opposite to
. Analogously, denote by
the circumcircle of
, and let
be the point on
which is diametrically opposite to
. Prove that
,
and
are collinear.
%V0
Let $ABC$ be an acute-angled triangle with orthocenter $H$, and let $W$ be a point on side $BC$. Denote by $M$ and $N$ the feet of the altitudes from $B$ and $C$, respectively. Denote by $\omega_1$ the circumcircle of $BWN$, and let $X$ be the point on $\omega_1$ which is diametrically opposite to $W$. Analogously, denote by $\omega_2$ the circumcircle of $CWM$, and let $Y$ be the point on $\omega_2$ which is diametrically opposite to $W$. Prove that $X$, $Y$ and $H$ are collinear.