第14章 全等三角形 学情评估
一、选择题(本大题共10小题,每小题4分,满分40分)
1.如图,△ABC和△DEF全等,且∠A=∠D,AC对应DE.若AC=6,BC=5.5,AB=5,则DF的长为( )
A.5.5 B.5 C.6 D.无法确定
INCLUDEPICTURE"J14-1.tif" INCLUDEPICTURE "D:\\课件\\八数HK安徽\\J14-1.tif" \* MERGEFORMATINET INCLUDEPICTURE "D:\\课件\\八数HK安徽\\J14-1.tif" \* MERGEFORMATINET INCLUDEPICTURE "D:\\课件\\八数HK安徽\\J14-1.tif" \* MERGEFORMATINET (第1题) INCLUDEPICTURE"J14-2.tif" INCLUDEPICTURE "D:\\课件\\八数HK安徽\\J14-2.tif" \* MERGEFORMATINET INCLUDEPICTURE "D:\\课件\\八数HK安徽\\J14-2.tif" \* MERGEFORMATINET INCLUDEPICTURE "D:\\课件\\八数HK安徽\\J14-2.tif" \* MERGEFORMATINET (第2题) INCLUDEPICTURE"F29.tif" INCLUDEPICTURE "D:\\课件\\八数HK安徽\\F29.tif" \* MERGEFORMATINET INCLUDEPICTURE "D:\\课件\\八数HK安徽\\F29.tif" \* MERGEFORMATINET INCLUDEPICTURE "D:\\课件\\八数HK安徽\\F29.tif" \* MERGEFORMATINET (第3题)
2.如图所示,AB=CD,AC=BD,则下列说法正确的是( )
A.可用“SAS”直接证明△AOB≌△DOC
B.可用“SAS”直接证明△ABC≌△DCB
C.可用“SSS”直接证明△AOB≌△DOC
D.可用“SSS”直接证明△ABC≌△DCB
3.如图,网格中有△ABC及线段DE,在网格中找一点F(必须在格点上),使△DEF与△ABC全等,这样的点F有( )
A.1个 B.2个 C.3个 D.4个
4.在测量一个小口容器的壁厚时,小明用“X型转动钳”按如图方法进行测量,其中OA=OD,OB=OC,测得AB=5 cm,EF=6 cm,则容器的壁厚是( )
A.5 cm B.6 cm C.2 cm D.0.5 cm
INCLUDEPICTURE"F30.tif" INCLUDEPICTURE "D:\\课件\\八数HK安徽\\F30.tif" \* MERGEFORMATINET INCLUDEPICTURE "D:\\课件\\八数HK安徽\\F30.tif" \* MERGEFORMATINET INCLUDEPICTURE "D:\\课件\\八数HK安徽\\F30.tif" \* MERGEFORMATINET (第4题) INCLUDEPICTURE"J14-3.tif" INCLUDEPICTURE "D:\\课件\\八数HK安徽\\J14-3.tif" \* MERGEFORMATINET INCLUDEPICTURE "D:\\课件\\八数HK安徽\\J14-3.tif" \* MERGEFORMATINET INCLUDEPICTURE "D:\\课件\\八数HK安徽\\J14-3.tif" \* MERGEFORMATINET (第5题)
5.已知△ABC如图,则甲、乙、丙三个三角形中和△ABC全等的是( )
A.甲、乙 B.乙、丙 C.只有乙 D.只有丙
6.已知△ABC≌△A′C′B′,有下列5个结论:①点B与点B′是对应顶点;②BC=C′B′;③AC=A′B′;④AB=A′B′;⑤∠ACB=∠A′B′C′.其中正确的结论有( )
A.1个 B.2个 C.3个 D.4个
7.根据下列条件,能画出唯一确定的三角形的是( )
A.AB=4,BC=8,AC=3
B.AB=4,∠B=30°,AC=3
C.AB=4,∠B=30°,∠C=45°
D.AB=4,∠C=90°
8.如图,△ABC≌△ADE,BC的延长线交DA于点F,交DE于点G,∠DGB=66°,∠E=105°,∠DAC=16°,则∠B的度数为( )
A.24° B.25° C.30° D.35°
INCLUDEPICTURE"J14-4.tif" INCLUDEPICTURE "D:\\课件\\八数HK安徽\\J14-4.tif" \* MERGEFORMATINET INCLUDEPICTURE "D:\\课件\\八数HK安徽\\J14-4.tif" \* MERGEFORMATINET INCLUDEPICTURE "D:\\课件\\八数HK安徽\\J14-4.tif" \* MERGEFORMATINET (第8题) INCLUDEPICTURE"J14-5.tif" INCLUDEPICTURE "D:\\课件\\八数HK安徽\\J14-5.tif" \* MERGEFORMATINET INCLUDEPICTURE "D:\\课件\\八数HK安徽\\J14-5.tif" \* MERGEFORMATINET INCLUDEPICTURE "D:\\课件\\八数HK安徽\\J14-5.tif" \* MERGEFORMATINET (第9题) INCLUDEPICTURE"初J+17.tif" INCLUDEPICTURE "D:\\课件\\八数HK安徽\\初J+17.tif" \* MERGEFORMATINET INCLUDEPICTURE "D:\\课件\\八数HK安徽\\初J+17.tif" \* MERGEFORMATINET INCLUDEPICTURE "D:\\课件\\八数HK安徽\\初J+17.tif" \* MERGEFORMATINET (第10题)
9.在如图所示的3×3网格中,△ABC是格点三角形(即顶点恰好是网格线的交点),则与△ABC有一条公共边且全等的所有格点三角形(不含△ABC)的个数是( )
A.3个 B.4个
C.5个 D.6个
10.如图,在△ABC中,∠C=90°,AD平分∠BAC,DE⊥AB于点E,有下列结论:①CD=ED;②AC+BE=AB;③∠BDE=∠BAC;④DA平分∠CDE;⑤S△ABD∶S△ACD=AB ∶AC.其中正确的有( )
A.5个 B.4个 C.3个 D.2个
二、填空题(本大题共4小题,每小题5分,满分20分)
11.如图,已知△ABC≌△EDF,点F,A,D在同一条直线上,AD是∠BAC的平分线,∠EDA=20°,∠F=60°,则∠DAC的度数是________.
INCLUDEPICTURE"J14-6.tif" INCLUDEPICTURE "D:\\课件\\八数HK安徽\\J14-6.tif" \* MERGEFORMATINET INCLUDEPICTURE "D:\\课件\\八数HK安徽\\J14-6.tif" \* MERGEFORMATINET INCLUDEPICTURE "D:\\课件\\八数HK安徽\\J14-6.tif" \* MERGEFORMATINET
(第11题)
INCLUDEPICTURE"J14-7.tif" INCLUDEPICTURE "D:\\课件\\八数HK安徽\\J14-7.tif" \* MERGEFORMATINET INCLUDEPICTURE "D:\\课件\\八数HK安徽\\J14-7.tif" \* MERGEFORMATINET INCLUDEPICTURE "D:\\课件\\八数HK安徽\\J14-7.tif" \* MERGEFORMATINET
(第12题)
12.如图,已知△ABE≌△ACD,且B,D,E,C共线,则下列结论:
①∠1=∠2;②∠BAD=∠CAE;③AD=AE;④DB=EC.
其中正确的是____________(填序号).
13.如图,△ABC≌△DEF,若测得∠A=∠D=90°,AB=3,DG=1,AG=2,则梯形CFDG的面积是________.
INCLUDEPICTURE"J14-8.tif" INCLUDEPICTURE "D:\\课件\\八数HK安徽\\J14-8.tif" \* MERGEFORMATINET INCLUDEPICTURE "D:\\课件\\八数HK安徽\\J14-8.tif" \* MERGEFORMATINET INCLUDEPICTURE "D:\\课件\\八数HK安徽\\J14-8.tif" \* MERGEFORMATINET (第13题) INCLUDEPICTURE"J14-9.tif" INCLUDEPICTURE "D:\\课件\\八数HK安徽\\J14-9.tif" \* MERGEFORMATINET INCLUDEPICTURE "D:\\课件\\八数HK安徽\\J14-9.tif" \* MERGEFORMATINET INCLUDEPICTURE "D:\\课件\\八数HK安徽\\J14-9.tif" \* MERGEFORMATINET (第14题)
14.如图,AB=AC,CD 和BE相交于点O,连接 BC.
(1)要使△ABE≌△ACD,应添加的条件是____________ (添加一个条件即可);
(2)在(1)的条件下,图中全等的三角形(不包括△ABE和△ACD)还有______对.
三、(本大题共2小题,每小题8分,满分16分)
15.如图,在Rt△ABC中,∠B=90°,CD∥AB,DE⊥AC于点E,且CE=AB.求证:△CED≌△ABC.
INCLUDEPICTURE"J14-10.tif" INCLUDEPICTURE "D:\\课件\\八数HK安徽\\J14-10.tif" \* MERGEFORMATINET INCLUDEPICTURE "D:\\课件\\八数HK安徽\\J14-10.tif" \* MERGEFORMATINET INCLUDEPICTURE "D:\\课件\\八数HK安徽\\J14-10.tif" \* MERGEFORMATINET
(第15题)
16.如图,在新修的小区中,有一条“Z”字形绿色长廊,其中AB∥CD,在AB,BC,CD三段绿色长廊上各修一小凉亭E,M,F,且BE=CF,点M是BC的中点,在凉亭M与F之间有一池塘,不能直接到达,要想知道M与F之间的距离,只需要测出线段ME的长度,则ME=MF,这样合适吗?请说明理由.
INCLUDEPICTURE"S-13.tif" INCLUDEPICTURE "D:\\课件\\八数HK安徽\\S-13.tif" \* MERGEFORMATINET INCLUDEPICTURE "D:\\课件\\八数HK安徽\\S-13.tif" \* MERGEFORMATINET INCLUDEPICTURE "D:\\课件\\八数HK安徽\\S-13.tif" \* MERGEFORMATINET
(第16题)
四、(本大题共2小题,每小题8分,满分16分)
17. 如图,在△ABC中,D是BC边上的一点,AB=DB,BE平分∠ABC交AC边于点E,连接DE.
INCLUDEPICTURE"J14-11.tif" INCLUDEPICTURE "D:\\课件\\八数HK安徽\\J14-11.tif" \* MERGEFORMATINET INCLUDEPICTURE "D:\\课件\\八数HK安徽\\J14-11.tif" \* MERGEFORMATINET INCLUDEPICTURE "D:\\课件\\八数HK安徽\\J14-11.tif" \* MERGEFORMATINET
(第17题)
(1)∠A与∠BDE相等吗?为什么?
(2)若∠A=100°,∠C=50°,求∠AEB的度数.
18.如图,已知OC平分∠AOB,P,Q是OC上不同的两点,PE⊥OA,PF⊥OB,垂足分别为点E,F,连接EQ,FQ.求证:
INCLUDEPICTURE"F37.tif" INCLUDEPICTURE "D:\\课件\\八数HK安徽\\F37.tif" \* MERGEFORMATINET INCLUDEPICTURE "D:\\课件\\八数HK安徽\\F37.tif" \* MERGEFORMATINET INCLUDEPICTURE "D:\\课件\\八数HK安徽\\F37.tif" \* MERGEFORMATINET
(第18题)
(1)△OPE≌△OPF;
(2)FQ=EQ.
五、(本大题共2小题,每小题10分,满分20分)
19.如图①,点A,B,C,D在同一直线上,AB=CD,作EC⊥AD于点C,FB⊥AD于点B,且AE=DF,连接AF,ED.
(1)求证:AF∥DE且AF=DE;
(2)若将△BFD沿AD方向平移得到图②,其他条件不变,(1)中的结论是否仍成立?请说明理由.
INCLUDEPICTURE"J14-12.tif" INCLUDEPICTURE "D:\\课件\\八数HK安徽\\J14-12.tif" \* MERGEFORMATINET INCLUDEPICTURE "D:\\课件\\八数HK安徽\\J14-12.tif" \* MERGEFORMATINET INCLUDEPICTURE "D:\\课件\\八数HK安徽\\J14-12.tif" \* MERGEFORMATINET (第19题)
20.如图,已知:正方形ABCD,E,F分别是BC,DC上的点,连接AE,AF,EF,且∠EAF=45°,求证:BE+DF=EF.
INCLUDEPICTURE"J14-13.tif" INCLUDEPICTURE "D:\\课件\\八数HK安徽\\J14-13.tif" \* MERGEFORMATINET INCLUDEPICTURE "D:\\课件\\八数HK安徽\\J14-13.tif" \* MERGEFORMATINET INCLUDEPICTURE "D:\\课件\\八数HK安徽\\J14-13.tif" \* MERGEFORMATINET (第20题)
六、(本题满分12分)
21.如图,直线y=-2x+4与x轴,y轴分别交于点A,B,过点A作AC⊥AB于点A,且AC=AB,点C在第一象限内.
INCLUDEPICTURE"J14-14.tif" INCLUDEPICTURE "D:\\课件\\八数HK安徽\\J14-14.tif" \* MERGEFORMATINET INCLUDEPICTURE "D:\\课件\\八数HK安徽\\J14-14.tif" \* MERGEFORMATINET INCLUDEPICTURE "D:\\课件\\八数HK安徽\\J14-14.tif" \* MERGEFORMATINET
(第21题)
(1)求点A,B,C的坐标;
(2)在第一象限内有一点P(3,t),使S△PAB=S△ABC,求t的值.
七、(本题满分12分)
22.如图①,AB=9 cm,AC⊥AB,BD⊥AB,垂足分别为点A,B,AC=7 cm.点P在线段AB上以2 cm/s的速度由点A向点B运动,同时点Q在射线BD上运动.它们运动的时间为t s(当点P运动结束时,点Q运动随之结束).
(1)若点Q的运动速度与点P的运动速度相等,当t=1时,△ACP与△BPQ是否全等?并判断此时线段PC和线段PQ的位置关系,请分别说明理由;
(2)如图②,若将“AC⊥AB,BD⊥AB”改为“∠CAB=∠DBA”,点Q的运动速度为x cm/s,其他条件不变,当△ACP与△BPQ全等时,求出x的值.
INCLUDEPICTURE"F38.tif" INCLUDEPICTURE "D:\\课件\\八数HK安徽\\F38.tif" \* MERGEFORMATINET INCLUDEPICTURE "D:\\课件\\八数HK安徽\\F38.tif" \* MERGEFORMATINET INCLUDEPICTURE "D:\\课件\\八数HK安徽\\F38.tif" \* MERGEFORMATINET
(第22题)
八、(本题满分14分)
23.如图,∠BAD=∠CAE=90°,AB=AD,AE=AC,AF⊥CB,交CB的延长线于点F.
(1)求证:△ABC≌△ADE;
(2)求∠FAE的度数;
(3)求证:CD=2BF+DE.
INCLUDEPICTURE"JJT14.tif" INCLUDEPICTURE "D:\\课件\\八数HK安徽\\JJT14.tif" \* MERGEFORMATINET INCLUDEPICTURE "D:\\课件\\八数HK安徽\\JJT14.tif" \* MERGEFORMATINET INCLUDEPICTURE "D:\\课件\\八数HK安徽\\JJT14.tif" \* MERGEFORMATINET
(第23题)
答案
一、1.B 2.D 3.D 4.D 5.B 6.C 7.C 8.B 9.B10.A
二、11.50° 12.①②③④
13.5 点拨:∵△ABC≌△DEF,
∴DE=AB=3,∠ABC=∠DEF,∴AB∥DE,
∴∠A=∠EGC=90°.
∵DG=1,
∴EG=DE-DG=3-1=2.
∵△ABC≌△DEF,
∴S△ABC=S△DEF,
∴易得S梯形CFDG=S梯形AGEB=(AB+EG)·AG
=×(3+2)×2=5.
14.(1)AD=AE(答案不唯一) (2)2
三、15.证明:∵DE⊥AC,∠B=90°,
∴∠DEC=∠B=90°.
∵CD∥AB,∴∠A=∠DCE.
在△CED和△ABC中,
∵
∴△CED≌△ABC(ASA).
16.解:合适.理由:∵AB∥CD,
∴∠B=∠C.
∵M是BC的中点,∴BM=CM.
在△BEM与△CFM中,
∵
∴△BEM≌△CFM(SAS).
∴EM=FM.
∴只需要测出线段ME的长度就可以知道M与F之间的距离.
四、17.解:(1)∠A=∠BDE,理由如下:
∵BE平分∠ABC,
∴∠ABE=∠DBE.
在△ABE和△DBE中,
∵
∴△ABE≌△DBE(SAS),∴∠A=∠BDE.
(2)∵∠A=100°,∠C=50°,
∴∠ABC=180°-∠A-∠C=180°-100°-50°=30°.
∵BE平分∠ABC,
∴∠DBE=∠ABC=×30°=15°,
∴∠AEB=∠DBE+∠C=15°+50°=65°.
18.证明:(1)∵OC平分∠AOB,PE⊥OA,PF⊥OB,
∴∠AOC=∠BOC,∠PEO=∠PFO=90°.
在△OPE和△OPF中,
∵
∴△OPE≌△OPF(AAS).
(2)∵△OPE≌△OPF,∴OE=OF.
在△OEQ和△OFQ中,
∵
∴△OEQ≌△OFQ(SAS),∴EQ=FQ.
五、19.(1)证明:∵AB=CD,
∴AB+BC=CD+BC,
即AC=BD.
∵EC⊥AD,FB⊥AD,
∴∠ACE=∠DCE=∠DBF=∠ABF=90°.
又∵AE=DF,
∴Rt△ACE≌Rt△DBF(HL).
∴CE=BF,
∴△DCE≌△ABF(SAS),
∴AF=DE,∠CDE=∠BAF,
∴AF∥DE.
(2)解:成立,理由如下:
∵AB=CD,
∴AB-BC=CD-BC,即AC=BD.
∵EC⊥AD,FB⊥AD,
∴∠ACE=∠DCE=∠DBF=∠ABF=90°.
又∵AE=DF,
∴Rt△ACE≌Rt△DBF(HL).
∴CE=BF,
∴△DCE≌△ABF(SAS),
∴AF=DE,∠CDE=∠BAF,
∴AF∥DE.
20.证明:如图,将△ABE绕点A逆时针旋转90°至△ADG的位置,使AB与AD重合,
INCLUDEPICTURE"DJ14-2.tif" INCLUDEPICTURE "D:\\课件\\八数HK安徽\\DJ14-2.tif" \* MERGEFORMATINET INCLUDEPICTURE "D:\\课件\\八数HK安徽\\DJ14-2.tif" \* MERGEFORMATINET INCLUDEPICTURE "D:\\课件\\八数HK安徽\\DJ14-2.tif" \* MERGEFORMATINET (第20题)
则AG=AE,∠DAG=∠BAE,DG=BE.
∵∠EAF=45°,
∴易得∠DAF+∠BAE=45°,
∴∠GAF=∠DAG+∠DAF=∠BAE+∠DAF=45°,
∴∠EAF=∠GAF.
由题意易得G,D,F三点共线.
在△AGF和△AEF中,
∵
∴△AGF≌△AEF(SAS).∴EF=GF.
∵GF=DG+DF=BE+DF,
∴BE+DF=EF.
六、21.解:(1)把x=0代入y=-2x+4中,
得y=4,∴B(0,4).
把y=0代入y=-2x+4中,
得x=2,∴A(2,0).过点C作CD⊥x轴于点D.
∵∠BAC=90°,
∴∠DAC+∠BAO=∠ABO+∠BAO=90°,
∴∠ABO=∠DAC.
在△ABO与△CAD中,∵
∴△ABO≌△CAD(AAS),
∴CD=OA=2,AD=OB=4,
∴OD=6,∴C(6,2).
(2)∵在第一象限内有一点P(3,t),使S△PAB=S△ABC,
∴CP∥AB.
设直线CP的表达式为y=-2x+b,
代入C的坐标得,2=-2×6+b,解得b=14.
∴直线CP的表达式为y=-2x+14.
把点P(3,t)的坐标代入得t=-2×3+14=8,
∴t的值为8.
七、22.解:(1)△ACP≌△BPQ,PC⊥PQ.
理由:∵AC⊥AB,BD⊥AB,
∴∠A=∠B=90°.
当t=1时,AP=BQ=2 cm,
∴BP=7 cm,∴BP=AC.
在△ACP和△BPQ中,
∵
∴△ACP≌△BPQ(SAS),
∴∠C=∠BPQ.
又∵∠C+∠APC=90°,
∴∠APC+∠BPQ=90°,
∴∠CPQ=90°,∴PC⊥PQ.
(2)①若△ACP≌△BPQ,
则AC=BP,AP=BQ,
可得7=9-2t,2t=xt,解得t=1,x=2.
②若△ACP≌△BQP,
则AC=BQ,AP=BP,可得7=xt,2t=9-2t,
解得t=,x=.
综上所述,当△ACP与△BPQ全等时,x的值为2或.
八、23.(1)证明:∵∠BAD=∠CAE=90°,
∴∠BAC+∠CAD=90°,∠CAD+∠DAE=90°,
∴∠BAC=∠DAE.
在△ABC和△ADE中,
∵
∴△ABC≌△ADE(SAS).
(2)解:∵∠CAE=90°,AC=AE,
∴△ACE是等腰直角三角形.
∴∠E=45°.
由(1)知△ABC≌△ADE,
∴∠BCA=∠E=45°.
∵AF⊥BC,∴∠CFA=90°,
∴∠CAF=45°.
∴∠FAE=∠CAF+∠CAE=45°+90°=135°.
(3)证明:延长BF到点G,使得FG=FB,连接AG.
∵AF⊥BC,∴∠AFG=∠AFB=90°.
在△AFB和△AFG中,
∵
∴△AFB≌△AFG(SAS).
∴AB=AG,∠ABF=∠G.
∵AB=AD,∴AG=AD.
∵△ABC≌△ADE,
∴∠CBA=∠EDA,CB=ED,
∴∠ABF=∠CDA,∴∠G=∠CDA.
由题意易得∠GCA=∠DCA=45°.
在△CGA和△CDA中,
∵
∴△CGA≌△CDA(AAS),∴CG=CD.
∵CG=CB+BF+FG=CB+2BF=DE+2BF,
∴CD=2BF+DE.