Question

Draw an angle ∠AOB as m∠AOB = 40°. 

Draw an angle ∠BOC such that ∠AOC = 90° 

Check whether m∠AOB + m∠BOC = m∠AOC.

Answer 1

Draw an angle ∠AOB = 40° and 

∠AOC = 90° on the same ray \(\overset\longrightarrow{OA}\)

Now, measure ∠AOB = 40° and ∠BOC = 50° 

∴ m∠AOB + m∠BOC = 40° + 50 = 90° 

m∠AOB + m∠BOC = 90° = m∠AOC

∴ m∠AOB + m∠BOC = m∠AOC.