Three lines AB, CD, and EF interesect each other at O.
If ∠AOE=30∘ and ∠DOB=40∘, find ∠COF.
110∘
From the given figure, we have
∠AOE+∠EOD+∠DOB=180∘ [∴Sum of all angles on a straight line is 180∘]⇒30∘+∠EOD+40∘=180∘⇒∠EOD=180∘−70∘⇒∠EOD=110∘
Again, ∠EOD=∠COF [vertically opposite angles]⇒∠COF=110∘