In Fig. 8.61, lines AB, CD and EF intersect at O. Find the measures of ∠AOC, ∠COF, ∠DOE and ∠BOF.
∠AOE + ∠EOB = 180o(Linear pair)
∠AOE + ∠DOE + ∠BOD = 180o
∠DOE = 105o
∠DOE = ∠COF = 105o(Vertically opposite angle)
∠AOE + ∠AOF = 180o(Linear pair)
40o + ∠AOC + 105o= 180o
∠AOC = 35o
Also,
∠BOF = ∠AOE = 40o(Vertically opposite angle)