Question

An exterior angle of A ABC is Z ACD. Prove that ZA + B = 2 ACD​

Answer 1

Just an example

Answer:

An exterior angle of a triangle is equal to the sum of the opposite interior angles.  

Hence, In this case ∠A and ∠B

So,  ∠A+∠B=140∘

as ∠A=∠B

or,2∠A=140∘

∠A=∠B=70 ∘