Let

is an inscribed quadrilateral in a circle

.

is the intersection point of the diagonals.

is the intersection point of

and

.

is the intersection point of

and

.

is the circumcircle of the triangle

.

is the circumcircle of the triangle

.

is the intersection point of

and

.

is the intersection point of

and

. Prove that

,

and

are collinear.