过E做EM⊥CB与CB的延长线交与M、做EN⊥AC,做EK⊥BD
∠ABC=110°
∠ABM=70°,∠CBD=40
∠ABD=70°
∠ABM=∠ABD
EM=EK
CE是角平分线
EM=EN
EK =EN
DE 平分∠ADM
∠ADE=40°
∠ADE=∠DCE+DEC
∠DCE=20°
∠DEC=20°