Question

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

(a) ${50}^{\circ }$

(b) ${60}^{\circ }$

(c) ${55}^{\circ }$

(d) ${65}^{\circ }$

Answer 1

ANSWER:
(d) 65°
We have:
OA = OB (Radii of a circle)
Let ∠ OAB = ∠ OBA = x °
In Δ OAB, we have:
x ° + x ° + 50° = 180° (Angle sum property of a triangle)
⇒ 2 x ° = (180° - 50°) = 130°
⇒ x=1302°=65°
Hence, ∠OAB = 65°