Q1 of 23 Page 274

In the figure, ‘O’ is the centre of the circle. ∠AOB = 100° find ∠ADB.

Given, ∠AOB = 100°


Join AB, which is a chord.


∠ ACB = (Angle subtended at the center is twice the angle subtended at circumference by the same chord)


⇒∠ ACB = 50


Now, ACBD is a quadrilateral and angles on the opposite sides in the quadrilateral are supplementary.


∠ ADB = 180-∠ ACB


⇒∠ ADB = 180-50


⇒∠ ADB = 130o


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