1.相等 设两点分别为E F
∵AD为角平分线
∴∠BAD=∠DAC
∵DE⊥AB DF⊥AC
∴∠AED=∠AFD=90°
∵AD=AD
∴△AED≌△AFD
∴DE=DF
2.S△ABD=1/2DE*AB
S△ADC=1/2DF*AC
∵DF=DE AB=2AC
∴S△ABD=2S△ADC
1.相等 设两点分别为E F
∵AD为角平分线
∴∠BAD=∠DAC
∵DE⊥AB DF⊥AC
∴∠AED=∠AFD=90°
∵AD=AD
∴△AED≌△AFD
∴DE=DF
2.S△ABD=1/2DE*AB
S△ADC=1/2DF*AC
∵DF=DE AB=2AC
∴S△ABD=2S△ADC