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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 : ∠DBA
Also, show that the ΔAOD is an equilateral triangle.
Solution
∠ADB = 90°
(Angle in a semicircle is a right angle)
∴ ∠DBA = 90° – ∠DAB
= 90° – 60°
= 30°
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