To Prove: AB bisects RS.
Proof: ∵ AB is the perpendicular bisector of PQ
∴ AB passes through the centre O.
| ∵ The perpendicular bisector of a chord of a circle passes through the centre
∵ PQ II RS
∴ AB 1 RS
∵ AB passes through the centre
∴ AB bisects RS.
| ∵ The perpendicular drawn from the centre of a circle bisects the chord.