Answer:
∠ 2 + ∠ 3 = 90°
Explanation:
note there is a right angle at A
∠ 1 and this right angle form a linear pair and sum to 180° , that is
∠ 1 + 90° = 180° ( subtract 90° from both sides )
∠ 1 = 90°
the sum of the 3 angles in Δ ABC = 180° , that is
∠ 1 + ∠2 ∠ 3 = 180° ( substitute ∠ 1 = 90° )
90° + ∠ 2 + ∠ 3 = 180° ( subtract 90° from both sides )
∠ 2 + ∠ 3 = 90°
∠ 4 is not required to obtain the sum of ∠ 2 + ∠ 3