Two circles of radius 13cm and 17cm intersect at A and B. What is the distance between the centres of the circles if AB = 24cm?

The perpendicular from the centre of a circle to a chord bisects the chord. The theorem states that if O is the centre and PQ is the chord, then the perpendicular OR from the centre O to the chord PQ bisects the chord PQ (i.e.) PR = RQ.