In ΔABC, ∠B = 50∘. Find ∠A, if ∠B is congruent to ∠C.
100∘
50∘
80∘
90∘
Since ∠C is congruent to ∠B, ∠C = 50∘.
Sum of the angles of a triangle = 180∘.
So, ∠A + ∠B + ∠C = 180∘
∠A = 180∘– (50∘ + 50∘) = 180∘ – 100∘ = 80∘