Answer:
∠ EDC = 55°
Step-by-step explanation:
Since Δ ADE is isosceles then the 2 base angles are congruent , then
∠ EDA = [tex]\frac{180-20}{2}[/tex] = [tex]\frac{160}{2}[/tex] = 80°
Similarly for Δ BCD
∠ CDB = [tex]\frac{180-90}{2}[/tex] = [tex]\frac{90}{2}[/tex] = 45°
The 3 angles on AB sum to 180° , that is
80° + ∠ EDC + 45° = 180°
∠ EDC + 125° = 180° ( subtract 125° from both sides )
∠ EDC = 55°
