Question
In figure, POQ is a line. Ray OR is perpendicular to line PQ. OS is another ray lying between rays OP and OR. Prove that


Solution
∵ Ray OR is perpendicular to line PQ.
∴ ∠QOR = ∠POR = 90° ...(1)
∠QOS = ∠QOR + ∠ROS ...(2)
∠POS = ∠POR - ∠ROS ...(3)
From (2) and (3),
∴ ∠QOS - ∠POS = (∠QOR - ∠POR) + 2∠ROS = 2∠ROS | Using (1)