∵AB=AC
∴∠B=∠C=70°
∵BD=CD
∴∠BAD=∠CAD=(180°-70°×2)/2=20°
∵AD=AE
∴∠ADE=∠AED=(180°-20°)/2=80°
∵∠AED=∠EDC+∠C
∴∠EDC=80°-70°=10°