Question

prove that the sum of three angles of a triangle is 180 degree​

Answer 1

Answer

*Refer to the attachment

Given

ABC is a triangle

To prove

∠A + ∠B + ∠C = 180°

Construction

Extend D from B

Proof

∠ABD + ∠ABC = 180° ( Linear pair)

---------> (1)

∠ABD = ∠ACB + ∠BAC ( Exterior angle is equal to the sum of the opposite interior angles)

---------> (2)

from equation (1)

∠ABD + ∠ABC = 180°

=> ∠ACB + ∠BAC + ∠BAC = 180° {From (2)}

=> ∠BAC + ∠ABC + ∠ACB = 180°

=> ∠A + ∠B + ∠C = 180°

Hence Proved

Answer 2

Answer:

Step-by-step explanation: