Question

What is the angle for a and b

Answer 1

It is an isosceles triangle, so
∠a = ∠b

180 - 40 = 140
140 ÷ 2 = 70°

∠a = 70°
∠b = 70°

------------------------------------------------------------------
Answer: ∠A = 70° , ∠B = 70°
------------------------------------------------------------------

Answer 2

angle A and B would be identical

a triangle is 180 degrees

180 - 40 = 140

140 /2 = 70

angle a and b are 70 degrees