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?

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You may also like to refer to Same Arc in the January 2000 Monthly Six and Concyclic in the February 2000 Monthly Six.