Q17 of 69 Page 9

In Fig. 9.43, if EC||AB, ∠ECD =70° and ∠BDO =20° , then ∠OBD is

Given,

EC ‖ AB


∠ECD = 70o


∠BDO = 20o


Since,


EC ‖ AB


And, OC cuts them so


∠ECD = ∠1 (Alternate angle)


∠1 = 70o


∠1 + ∠3 = 180o (Linear pair)


∠3 = 110o


In


∠BOD + ∠OBD + ∠BDO = 180o


∠3 + ∠ODB + 20o = 180o


∠ODB = 50o

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