如图ac平行df平行bd求证ad
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![如图ac平行df平行bd求证ad](/uploads/image/f/3627515-11-5.jpg?t=%E5%A6%82%E5%9B%BEac%E5%B9%B3%E8%A1%8Cdf%E5%B9%B3%E8%A1%8Cbd%E6%B1%82%E8%AF%81ad)
证明:∵AC∥DE∴∠A=∠D∵BC∥EF∴∠ABC=∠DFE∵AB=AF+BF、DF=DB+BF、AF=DB∴AB=DF∴△ABC≌△DFE(ASA)∴AC=DE
过点A作直线GH平行于BC∵GH平行于BC∴∠GAB=∠B∠HAC=∠C(两直线平行,内错角相等)又∵∠GHA=180°∴∠GAB+∠BAC+∠HAC=180°∴∠A+∠B+∠C=180°
1.∵AC=BD,∴AC+CB=BD+CB∴AB=CD∵AB=CD,AE=CF,BE=DF,∴△AEB≌△CFD(SSS)∴∠A=∠FCD∴AE∥CF2.∵BE⊥AD,CF⊥AD∴∠BED=∠CFD=
证明:∵AE∥DF【已知】∴∠A=∠D【两直线平行,内错角相等】∵AC=BD【已知】∴AB=AC-BC=BD-BC=CD【公理,等量减等量差相等】又∠ABE=∠DCF【已知】∴△ABE≌△DCF【角.
∵BE=CF∴BE+EC=CF+EC即BC=EF∵AB=DE,AC=DF∴△ABC≌△DEF(S.S.S)∵∠B=∠DEF,∠ACB=∠F∴AB∥DE,AC∥DF
证明:∵AE∥DF∴∠A=∠D∵AB=AC-BC,CD=BD-BC,AC=BD∴AB=CD∵∠ABE=∠DCF∴△ABE≌△DCF(ASA)
证明:(1)∵DE//AC,DF//BC∴四边形DECF是平行四边形∴DE=CF∵DE//AC∴DE/AC=BE/BC∵BE/BC+EC/BC=1∴FC/AC+EC/BC=1(2)∵DF//BC∴CF
∵DE//OA,AE//OD∴四边形AODE是平行四边形则DE=OA,AE=OD而在平行四边形ABCD中,对角线AC、BD相交于点O∴OA=OC,OB=OD即DE=OC,AE=OB那么AE//=OB,
证明:∵DE//AC,CE//BD∴四边形OCED是平行四边形∵四边形ABCD是矩形∴OC=OD(矩形的对角线相等且互相平分)∴四边形OCED是菱形(邻边相等的平行四边形是菱形)
应该是CF∥AB证明:∵D是AB的中点AE=EC即E是AC的中点∴DE是△ABC的中位线∴DE∥BC即DF∥BC∵CF∥AB即CF∥BD∴四边形DBCF是平行四边形∴BD=CF
∵AB⊥BC,AE⊥EF(已知)∴∠ABC和∠DEF是直角三角形∵BE=CF(已知)EC=EC(重叠的边)BC=BE+ECEF=CF+EC∴BC=EF(等量代换)在RT△ABC和RT△DEF中∵{AC
∵DE//AB已知∴∠1=∠2两直线平行,内错角相等∵DF//AC已知∴∠2=∠A两直线平行,内错角相等∴∠1=∠A等量代换
证明:因为AB平行DE所以DE/AB=OD/OA=OE/OB因为EF平行BC所以EF/BC=OE/OB所以CD/AB=EF/BC因为AC平行DF所以DF/AC=OD/OA所以DF/AC=DE/AB=E
答证明:因为AB平行DE所以∠ABC=∠DEF(两直线平行,同位角相等)因为BE=CF,CE=CE所以BE+CE=CF+CE所以BC=EF(等式的性质)在△ABC和△DEF中(AB=DE(∠ABC=∠
木有图耶?我自己猜了个图,不知是否正确?∵AE=BD∴AE-AD=BD-AD∴DE=AB∵AC=DF,∠CAB=∠FDE∴△ABC≌△DEF∴∠B=∠E∴BC//EF
∵EG∥AD∴EG/AD=BE/AB∵HF∥AD∴HF/AD=CF/DC∵AD∥EF∥BC∵BE/AE=CF/DF∴BE/AB=CF/DC(比例的性质)∴EG/AD=HF/AD∴EG=HF再问:EG/
证明:作半径OE⊥AB交圆于E点.∵AB∥CD,∴OE⊥CD,∴AE^=BE^,CE^=DE^∴AE^-CE^=BE^-DE^即:AC^=BD^.注:^即为弧的标志
AB//CD∴CAB+ABD=180又有ABP+P+BAP=180∴ABP+P+BAP=CAP+BAP+ABP+PBD即P=PAC+PBD