Let PQ be a chord of a circle with centre O and radius 13cm such that PQ = 24cm.
From O, draw OM perpendicular PQ and join OP.
As, the perpendicular from the centre of a circle to a chord bisects the chord.
∴ PM = 12cm
In △OMP, we have
OP2 = OM2 + PM2
⇒ 132 = OM2 + 122
⇒ OM = 5cm. Hence, the distance of the chord from the centre is 5cm.