解:∵DE为AB的垂直平分线 ∴AD=BD ∴∠A=∠ABD ∵AB=AC,∠ABC=70° ∴∠ABC=∠C=70°, ∠A=180°-70°-70°=40° ∵∠A=∠ABD ∴∠ABD=40° ∴∠DBC=∠ABC-∠ABD=70°-40°=30°
哪来的D啊
30°