Question

prove that the sum of all in triangle is 180

Answer 1

Hope it will help u!

Answer 2

let's take a triangle ABC
Construction: EF ll BC
since EF ll BC ,
angle 4 = angle 2 ......( alternate interior angle)
and angle 5= angle 3 ( alternate interior angle)

now, angle 4+ angle 1 + angle 5= 180...( sum of angles on same segment is 180)
(or) angle 2 +angle 1+ angle 3 =180
Hence proved