如图，∠ABC>∠ADC，且∠BAD的平分线AE与∠BCD的平分线CE交于点E，则∠AEC与∠ADC、∠ABC之间存在的等量关系是（）A.∠AEC=∠ABC-2∠ADCB.∠AEC=∠ABC-∠ADC2C.∠AEC=12∠ABC-∠ADCD.∠AEC=∠ABC-

Question

如图，∠ABC>∠ADC，且∠BAD的平分线AE与∠BCD的平分线CE交于点E，则∠AEC与∠ADC、∠ABC之间存在的等量关系是（　　）

A. ∠AEC=∠ABC-2∠ADC

B. ∠AEC=

(∠ABC-∠ADC)/(2)

C. ∠AEC=

(1)/(2)∠ABC-∠ADC

D. ∠AEC=

(∠ABC-∠ADC)/(3)

Answer 1

如图，延长BC交AD于点F，∵∠BFD=∠B+∠BAD，∴∠BCD=∠BFD+∠D=∠B+∠BAD+∠D，∵CE平分∠BCD，AE平分∠BAD∴∠ECD=∠ECB=12∠BCD，∠EAD=∠EAB=12∠BAD，∵∠E+∠ECB=∠B+∠EAB，∴∠E=∠B+∠EAB-∠ECB=∠B+∠BAE-...