Question

Three lines AB, CD and EF intersect each other at O. If AOE = 30° and DOB = 40°,
Find COF

Answer 1

Given, 

∠AOE = 30°

∠DOB = 40°

So, ∠EOD = 180 - (30+40)           [angles on a straight line]

                 =  180 - 70

                 =  110

∠EOD = ∠COF                             [ vertically opposite angle]

∴ ∠COF = 110°

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Figure in the attached pic.

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Answer 2

Step-by-step explanation:

we know

linear pair - 180°

given

angle BOD =40°

angle AOE = 30°

angle EOD = 180 - ( 40 +30)

= 110°

we know

vertically opposite angles are always equal.

angle EOD is vertically opposite to COF

COF = EOD

=110°

HOPE THIS WILL HELP YOU