4) Prove that the sum of measure of all angles in a triangle is 180°. fast plzzzzz Question 4) Prove that the sum of measure of all angles in a triangle is 180°.fast plzzzzz in progress 0 Math Natalia 3 weeks 2021-09-04T01:26:00+00:00 2021-09-04T01:26:00+00:00 2 Answers 0 views 0

## Answers ( )

Given :

A triangle ABC.

To prove :

∠A+∠B+∠C=180°

⟹∠1+∠2+∠3=180°

Construction :

Through A, draw a line l parallel to BC.

Proof :

Since l∥BC. Therefore,

∠2=∠4 …….eq(i)

And, ∠3=∠5……eq(ii)

adding eq(i)and(ii)

Therefore, ∠2+∠3=∠4+∠5

∠1+∠2+∠3=∠1+∠4+∠5 [adding∠1bothSide]

∠1+∠2+∠3=180 °

Thus, the sum of three angles of a triangle is 180° .

Answer:all sides of a triangle are equal so angle formed between them will also be equal