Q18 of 69 Page 9

In Fig. 9.44, x + y =

By exterior angle theorem,

In


∠OCA + ∠AOC = x


x = 80o + 40o


= 120o


∠AOC = ∠DOB (Vertically opposite angle)


∠DOB = 40o


By exterior angle theorem,


In


y = ∠BOD + ∠ODB


= 40o + 70o


= 110o


Now, x + y = 230o

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