In the figure below, lines AB and CD intersect at O. If ∠AOC + ∠BOE = 70∘ and ∠BOD = 40∘, find (2∠BOE).
60∘
∠AOC+∠BOE+∠COE=180∘ (AOB is a straight line)
Given, ∠AOC+∠BOE=70∘
So, ∠COE=180∘–(∠AOC+∠COE)
⇒180∘–70∘=110∘
Again, ∠COE+∠BOE+∠BOD=180∘ (COD is a straight line)
We know that, ∠COE=110∘ and ∠BOD=40∘
So, ∠BOE=180∘–∠COE−∠BOD
⇒∠BOE=180∘–110∘−40∘=30∘⇒2∠BOE=60∘