!、1 ～ 4.BCDD 5 ～ 6.CB"、7. #8. 79. 125°，55°，125°，55°10. 5，511. 3cm12. 70°$、13.%：&’()*+,-，.’/0,1234, n23（n5,67），8（n - 2）× 180° = 155° × n，69，: 25° × n = 360°.%: n = 725.;5<:= n>?567，@A?BCDE4 155°=,123.@A()=*+?,-.14.%：∵ F23 ABCD 5GHF23，∴ AD ∥ BC，∴ ∠DAE = ∠AEB.∵ AE GI ∠BAD，∴ ∠DAE = ∠BAE.∴ ∠BAE = ∠AEB，∴ AB = BE.∵ AB ∶AD = 3 ∶5，’ AB = 3x，8 AD = 5x.∴ EC = BC - BE = AD - AB = 5x - 3x = 4.∴ x = 2.∴ AB = 3x = 6cm，AD = 5x = 10cm.∴ ?ABCD =JK5 32cm.15.∠DAE = 20°.16.LM：∵ N E、F IO52 BC、AC =PN，∴ EF ∥ AB，EF = 12 AB.Q ∵ AD = 12 AB，∴ AD = EF.∴ F23 AEFD 4GHF23.∴ DF = AE.F、17.LM：∵ BD、CE IO5 AC、AB 2R=PS，∴ AE = BE，AD = CD，∴ DE瓛 12 BC.∵ N M 、N IO4 BG、CG =PN，∴ M N瓛 12 BC.∴ ED瓛M N.∴ F23 M EDN 4GHF23.#、18.%：（1）TUGI；（2）V.9WXY：Z[ EN、NF、FM 、M E.W\].: BN = DM ，AE = CF.∵ F23 ABCD 4GHF23，∴ ∠B = ∠D，AB = CD.∴ AB - AE = CD - CF，∴ BE = DF.∴ △BNE ≌ △DM F，∴ NE = M F.^9.: M E = NF.∴ F23 M ENF 4GHF23.∴ EF _ M N TU
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