Abc早期教育幻灯片 ∫△ABC和△ △DEF是直角三角形，BC=EF，AC=DF。∴Rt△ABC≌Rt△DEF(HL)∴∠ABC=∠DEF∠∠DEF+∠DFE = 90∴∠ABC+∠DFE=90。所以填90