Question

prove that the sum of angles of a triangle is 180°​

Answer 1

Step-by-step explanation:

A triangle ABC.

To prove :

∠A+∠B+∠C=180o⟹∠1+∠2+∠3=180o

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=180o

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



Answer 2

Answer:

first draw a line perpendicular to the side BC from A

name it pq

angle pab=abc(alternate interior angles)

angle qac= acb(alternate interior angles)

pab + bac+caq =180

hence proved

Step-by-step explanation:

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