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In Fig. ABCD is a quadrilateral inscribed in a circle with centre O. CD is produced to E such that ∠AED = 95° and ∠OBA = 30°. Find ∠OAC. |
Answer» ∠ADE = 95°(Given) Since, OA = OB, so ∠OAB = ∠OBA ∠OAB = 30° ∠ADE + ∠ADC = 180° (Linear pair) 95° + ∠ADC = 180° ∠ADC = 85° We know that, ∠ADC = 2∠ADC ∠ADC = 2 x 85° ∠ADC = 170° Since, AO = OC (Radii of circle) ∠OAC = ∠OCA (Sides opposite to equal angle) ... (i) In triangle OAC, ∠OAC + ∠OCA + ∠AOC = 180° ∠OAC + ∠OAC + 170° = 180° [From (i)] 2∠OAC = 10° ∠OAC = 5° Thus, ∠OAC = 5° |
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