In the given figure, \(POQ\) is a line. Ray \(OR\) is perpendicular to line \(PQ\). \(OS\) is another ray lying between rays \(OP\) and \(OR\). Prove that \(∠ROS = (\frac{1}{2}) (∠QOS – ∠POS)\)?
 
YCIND_231205_5809_13.png
 
Proof:
 
\(POQ\) is a straight line.
 
So, the sum of all angles made on it is \(^°\)
 
\(∠POS + ∠ROS + ∠ROQ =\) \(^°\) 
 
Since \(∠ROQ =\)\(^°\), \(∠POS + ∠ROS +\)\( =\)\(^°\) 
 
\(∠POS + ∠ROS =\)\(^°\)
 
\(∠ROS =\)\(^°  – ∠POS\) ---(2)
 
From figure, \(∠ROS + ∠ROQ = ∠\)   
 
That is, \(∠ROS +\)\(^° = ∠QOS\)
 
\(∠ROS = ∠QOS –\)\(^°\) –---(2) 
 
Now Adding both the equations (1) and (2) we get, 
 
\(∠ROS + ∠ROS =\)\(^° – ∠POS + ∠QOS –\)\(^°\)
 
\(2∠ROS =(∠QOS  – ∠POS)\)
 
\(∠ROS = \frac{1}{2}(∠QOS – ∠POS)\)
 
Hence Verified.