Question

1. You have to find: ∠B=

Answer 1

∠B≅∠A a(angles opposite equal sides CB and CA)

40°+2(∠B)=180°(sum of ∠`s of a triangle)

2(∠B)=180°-40°

2(∠B)=140°

∴∠B=70°

I hope this helps you. I replaced ∠A by ∠B because they are equal.