ABC is a triangle in which AB = AC. The base BC is produced to D. If ∠ACD = 130∘, then ∠A = ___.
80°
∠ACD = 130∘ ........ (given)
∠ACB =50∘ ....... (linear pair)
Given that AB = AC
∠ABC = ∠ACB = 50∘ ..... (base angles of an isosceles triangle)
Therefore,∠A + 50° = 130° ..... (exterior angle theorem)
∠A = 80∘