Y by Mango247
Let
be a line and let
be two points on
. Circles
and
centred at
and
respectively are both tangent to
at
, with
and
being on opposite sides of
. Circles
and
centred at
and
respectively are both tangent to
at
, with
and
being on opposite sides of
. Moreover
and
are on the same side of
. Prove that if there exists a circle tangent to all circles
containing all of them in its interior, then the lines
and
are either concurrent or parallel.


























