
It is given that (OR ⊥ PQ) and \(∠\)POQ = 180°

We can rewrite it as \(∠\)ROP = \(∠\)ROQ = 900
Since, \(∠\)ROP =\(∠\)ROQ
It can be written as
\(∠\)POS + \(∠\)ROS = \(∠\)ROQ
\(∠\)POS + \(∠\)ROS = \(∠\)QOS – \(∠\)ROS
\(∠\)SOR + \(∠\)ROS = \(∠\)QOS – \(∠\)POS
\(⇒\) 2\(∠\)ROS = \(∠\)QOS – \(∠\)POS
i.e, \(∠\)ROS = \(\frac{1}{2}\) (\(∠\)QOS – \(∠\)POS)


