
P is the centre of the circle.
AB = 23 cm
seg PQ ⊥ chord AB
Perpendicular drawn from the centre of the circle to the chord bisects the chord.
So, the length of l(QB) = \(\frac{1}{2}\) l(AB)
l(QB) = \(\frac{1}{2}\) ×23 ...[∵ l(AB) = 23 cm]
l(QB) = 11.5 cm