Answer:
∠ 1 = 109° , ∠ 2 = 71° , ∠ 3 = 109°
Explanation:
∠ 1 and ∠ 4 are a linear pair and sum to 180° , that is
∠ 1 + ∠ 4 = 180° ( substitute ∠ 4 = 71° )
∠ 1 + 71° = 180° ( subtract 71° from both sides )
∠ 1 = 109°
∠ 2 and ∠ 4 are vertically opposite angles and are congruent (equal), so
∠ 2 = ∠ 4 = 71°
∠ 3 and ∠ 1 are vertically opposite angles and are congruent , then
∠ 3 = ∠ 1 = 109°