I am unable to understand this property of lines and angles. Could any expert explain this line please and make it easier for me to understand? Share with your friends Share 0 Saksham Tolani answered this Dear Student, In the above figure,∠AOC and ∠COB are adjacent angles.And, ray OC is common arm and ray OA and OB are non common arms.Given,sum of two adjacent angle is 180°.⇒they form a linear pair of angle.⇒they are in same straight line.⇒ray OA and OB are in the opposite direction.⇒the non common arms are two opposite rays. Regards! 1 View Full Answer