Question

in triangle ABC, angle A=120 degrees, AB=BC find angle B and angle C.​

Answer 1

Answer:

Angles A and B = 180 - 120 = 60/2 = 30° each

Answer 2

Answer:

∠ABC = ∠ACB = 30°

Step-by-step explanation:

If AB=BC then the triangle is isosceles at B. In an isosceles triangle, the base angles have the same degree measure and are, as a result, equal (congruent), so A=C

A triangle's angles add up to 180 degrees

But according to the problem, angle A equals angle C equal to 120 degrees, add up to 240 degrees. It's mistake.  

I think AB=AC

∠BAC+∠ABC+ACB=180°

∠ABC+ACB = 180° - 120° = 60°

ΔABC: AB=AC => ΔABC - ISOSCELES TRIANGLE => ∠ABC = ∠ACB = 30°