∠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°