CBSE Class 10 Maths (Basic) 2025 · Paper 430/4/1 · Question 24(b)

Since $\angle OAP=\angle OBR=90^{\circ }$ (tangent is perpendicular to the radius) and $O$ lies on $AB$, the co-interior angles $\angle BAP$ and $\angle ABR$ made by the transversal $AB$ add up to $180^{\circ }$, so $PQ\parallel RS$. The tangents at the ends of a diameter are parallel. Hence proved.