Q21 of 141 Page 447

In the given figure, O is the centre of a circle. Then, ∠OAB = ?

Given: and


In ΔOAB


Here,


OA = OB (radius)


Let ∠OBA = ∠OAB = x (angles opposite to equal sides are equal)


By angle sum property


∠AOB + ∠OBA + ∠OAB = 180°


50° + x + x = 180°


2x = 180° – 50°


2x = 130°


x = 60°


∴ ∠OAB = 60°

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