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In ∆ABC, ∠ABC = 70°, ∠BCA = 40°. O is the point of intersection of the perpendicular bisectors of the sides, then the angle ∠BOC is
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- 100°
- 120°
- 130°
- 140°
- 100°
Correct Option: D
On the basis of question we draw a figure of ∆ABC , 
Given that , ∠ABC = 70°, ∠BCA = 40°
OA = OB = OC = Circum-radius
In ∆ ABC,
∠A = 180° – 70° – 40° = 180° – 110° = 70°
The angle subtended by an arc at the centre is twice to that at the circumference.
∴ ∠BOC = 2∠BAC
∠BOC = 2 × 70 = 140°
