Make AE coincide with AB, e to f, even AC, AF,

∠∠b+∠E = 180 & amp； # 186; ，∠E=∠ABF，

∴ Divide the lines C, B and F***,

Let CD=BC+DE=CF, AD=AF, AC as the public party,

∴△ACD≌△ACF(SSS)

∴∠F=∠ADC，

∫∠F =∠ADE，

∴∠ADC=∠ADE，

In other words, AD divides ∠CDE in two.