Question

what is the sum of triangle A, B, C​

Answer 1

Answer:

The three angles A', B', and C' form together with a straight angle (they are along the line l). So, their angle sum is 180°. But then the angle sum ∠A + ∠B + ∠C must also be 180°. 3.

Answer 2

Answer:

the sum of a angles of a triangle ABC is always 180° because of angle sum property of triangle.

p.s.- please explain ur question correctly