Question

如图,de分别是△abc的边bc,ac上的点.且ab=ac,ad=ae

Answer 1

∵AB=AC ∴∠ABC=∠ACB

又∵AD=AE ∴∠ADE=∠AED

∴∠ADC=∠ADE+∠EDC=∠AED+∠ACB=∠BAD+∠ABC

又∠AED=∠EDC+∠ACB

∴2∠EDC+∠ACB=∠BAD+∠ABC

∴2∠EDC=∠BAD

1.若∠BAD=20°,则∠EDC=10º

2问题不完整

3.设∠BAD=α,∠EDC=β,则2β=α