The Total solution for NCERT class 6-12
∠B = 600, ∠C = 800 (given)
As per question:
∠OBC = 600/2= 300 and
∠OCB = 800/2= 400
In triangle BOC,
∠OBC + ∠OCB + ∠BOC = 180 0
[Sumof angles of a triangle = 1800]
300 +400 + ∠BOC = 1800
∠BOC = 1100