Answer:
∠ A = 72°
Step-by-step explanation:
The sum of the 3 angles in a triangle = 180°, thus
∠ ECD = 180° - (90 + 54)° = 180° - 144° = 36°
∠ ACB = ∠ ECD = 36° ( vertical angles )
Since AC and BC are congruent then Δ ABC is isosceles, thus the base angles are congruent, that is
∠ A = ∠ B
∠ A = [tex]\frac{180-36}{2}[/tex] = [tex]\frac{144}{2}[/tex] = 72°
