Question

Prove that the sum of the angles of a triangle is 180° ?

Answer 1

Answer:

Step-by-step explanation:

Given :

A triangle ABC.

To prove :

∠A+∠B+∠C=180  degree

⟹∠1+∠2+∠3=180  degree

 

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  degree

 

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

Hope it helps :)

Answer 2

Answer:

triangles has three sides and three vertices

Step-by-step explanation:

now x × X × X = 180

3X = 180

X = 180÷ 3

X = 60