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In the given figure, AB is a diameter of the circle with centre O. DO is parallel to CB and ∠DCB = 120°. Calculate : ∠DBC Also, show that the ΔAOD is an equilateral triangle.

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Question

In the given figure, AB is a diameter of the circle with centre O. DO is parallel to CB and ∠DCB = 120°. 

Calculate : ∠DBC 

Also, show that the ΔAOD is an equilateral triangle.

Sum
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Solution


OD = OB

∴ ∠ODB = ∠OBD

Or ∠ABD = 30°

Also, AB || ED

∴ ∠DBC = ∠ODB = 30°  (Alternate angles)

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