The central angle ∠BOC and the inscribed angle ∠BAC lie on arc BC. ∴ ∠BOC = 2 × ∠BAC = 60° Again, the central angle ∠COD and the inscribed angle ∠CAD lie on arc CD. ∴ ∠CAD = ½ × ∠COD = 60° ∴ ∠DAB = ∠CAD + ∠BAC = 60° + 30° = 90° Since ABCD is a cyclic quadrilateral, ∴ ∠BCD = 180° − ∠DAB = 180° − 90° = 90° So, the values are: ∠BOC = 60° and ∠BCD = 90°.