A, B and C are three points on a circle such that the angles subtended by the chords AB and AC at the centre O are 80° and 120°, respectively. The value of ∠BAC is:

70° 85° 75° 80°

80°

∠AOB + ∠AOC + ∠BOC = 360º 80º + 120º + ∠BOC = 360º ∠BOC = 160º Angle made by an arc on centre is double to that made by same arc on circumference. So, ∠BAC = \(\frac{∠BOC}{2}\) = \(\frac{ 160º}{2}\) = 80º