Question

prove the sum of angle of a triangle is 180 degree​

Answer 1

Answer:

Step-by-step explanation:

Answer 2

ABC is a triangle.

Through point A draw the line EF∥BC.

⇒  ∠ABC=∠EAB           [ Alternate angles ]

⇒  ∠BCA=∠FAC           [ Alternate angles ]

l

⇒  ∠EAB+∠BAC+∠FAC=180°           [ Linear pairs ]

By substituting ∠EAB=∠ABC and ∠FAC=∠BCA

⇒  ∠ABC+∠CAB+∠ACB=180°

∴  The sum of all the three angles in a triangle is 180°