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प्रश्न
In figure ∠ABC = 120°, where A, B and C are points on the circle with centre O. Find ∠OAC?
उत्तर
Reflex ∠AOC = 2∠ABC
= 20 × 120°
= 240°
∴ ∠AOC = 360° – 240°
= 120°
∠OCA + ∠OAC = 180° – 120°
= 60°
∴ ∠OAC = `60/2`
= 30° ...(Since OA = OC)
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