1问:∵AD∥BC,∠B=∠C;∴∠1=∠B=∠C=60°;∴∠ADC=120°
2问:AB∥DF且AB=DF。证明:DF是∠ADC的平分线,∴∠ADF=∠1,所以DF∥AB。又∵AD∥BC,∴四边形ABFD是平行四边形,∴AB=DF