Y by VicKmath7, itslumi, Mango247, Rounak_iitr
Let
be an acute triangle, with
. Let
be the midpoint of the arch
that does not contain
and let
be the midpoint of
. Let
be the
-excenter and
-excenter of
, respectively. Let
be the reflection of
with respect to
. Prove that the points
are concyclic.














