Question

proof some of all angle of a triangle equal to 180​

Answer 1

In order to prove that the sum of angles of a triangle is 180, you must know the theorems of angles of a triangle.

We know that,  alternate interior angles are of equal magnitude.

This'll help us get the answer. Let us assume a triangle ABC. Now we have to substitute the angles.

∠PAB + ∠BAC + ∠CAQ = 180°. where PQ line parallel to side BC touching vertex A.

∠PAB = ∠ABC & ∠CAQ = ∠ACB BECAUSE alternate interior angles are congruent..

Hence we get, ∠ABC + ∠BAC + ∠ACB = 180°  

Answer 2

Given :-A triangle ABC .

To prove :- <BAC + <B +< C = 180

Construction :- draw a line PM parallel to parallel to BC prove through A.

Proof :- <PAB + < BAC +<MAC = 180........(1) {by straight angle's sum}


Now,

< PAB=<B..(2) {pair of}
<MAC = <C. {alternate
..(3) {interior
<s}
From (1), (2) and (3), we get

<BAC +<C +<B = 180