Y by
In a right triangle
, angle
is a right ,
. A circle
is circumscribed around the triangle
. The tangent to
at point
intersects the line
at point
. Point
is the midpoint of the arc
of circle
not containing point
. The line
intersects the circle
at points
and
. The tangent to
at
intersects the line
at point
. Prove that the angle
is right .





















