Two perpendicular chords of a circle meet at a point P inside the circle and cut off arcs $a$, $b$, $c$ and $d$ on the circumference of the circle.

P may be moved anywhere inside the circle but the chords always remain perpendicular to each other.

What is the relationship between the arcs $a$, $b$, $c$ and $d$?

You may also like to refer to Same Arc and Concyclic .