Question

如图,D是△ABC的BA边延长线上一点,∠B=∠C,AE‖BC.试说明AE是∠DAC的平分线

Answer 1

AE∥BC．

∵AB=AC,

∴∠B=∠C,

∵AE平分∠DAC,

∴∠DAE=∠CAE,

又∵∠DAE+∠CAE=∠B+∠C,

∴2∠DAE=2∠B,即∠DAE=∠B,

∴AE∥BC．