2012年全国中考数学试题分类解析汇编(159套63专题)专题43平行四边形.pdf
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1、精心整理2012 年全国中考数学试题分类解析汇编(159 套 63 专题)专题 43:平行四边形一、选择题1.(2012 广东佛山 3 分)依次连接任意四边形各边的中点,得到一个特殊图形(可认为是一般四边形的性质),则这个图形一定是【】A平行四边形B矩形C菱形D梯形【答案】A。【考点】三角形中位线定理,平行四边形的判定。【分析】根据题意画出图形,如右图所示:连接 AC,四边形 ABCD 各边中点是 E、F、G、H,HG AC,HG=12AC,EF AC,EF=12AC。EF=GH,EF GH。四边形 EFGH 是平行四边形。由于四边形 EFGH 是平行四边形,它就不可能是梯形;同时由于是任意四
2、边形,所以 AC=BD或 AC BD不一定成立,从而得不到矩形或菱形的判断。故选 A。2.(2012 浙江杭州3 分)已知平行四边形ABCD 中,B=4 A,则 C=【】A18B 36C72D144【答案】B。【考点】平行四边形的性质,平行线的性质。【分析】由平行四边形性质求出 C=A,BC AD,推出A+B=180 ,求出A 的度数,即可求出C:四边形ABCD 是平行四边形,C=A,BC AD。A+B=180。B=4 A,A=36。C=A=36。故选B。3.(2012 湖北武汉 3 分)在面积为 15 的平行四边形 ABCD 中,过点 A作 AE垂直于直线 BC于点 E,作 AF垂直于直线
3、CD于点 F,若 AB 5,BC 6,则 CE CF的值为【】精心整理A1111 32B1111 32C 1111 32或 1111 32D 1111 32或 132【答案】C。【考点】平行四边形的性质和面积,勾股定理。【分析】依题意,有如图的两种情况。设BE=x,DF=y。如图 1,由 AB 5,BE=x,得222AEABBE25x。由平行四边形 ABCD 的面积为 15,BC 6,得2625x=15,解得5 3x=2(负数舍去)。由 BC 6,DF=y,得222AFADDF36y。由 平 行 四 边 形ABCD的 面 积 为15,AB 5,得253 6y=1 5,解得y=3 3(负数舍去)
4、。CE CF=(65 32)(53 3)=1111 32。如图 2,同理可得 BE=5 32,DF=3 3。CE CF=(65 32)(53 3)=1111 32。故选 C。4.(2012 湖南益阳4 分)如图,点A是直线 l 外一点,在l 上取两点B、C,分别以A、C为圆心,BC、AB长为半径画弧,两弧交于点D,分别连接AB、AD、CD,则四边形ABCD 一定是【】A平行四边形B矩形C菱形D梯形【答案】A。【考点】作图(复杂作图),平行四边形的判定。【分析】别以 A、C为圆心,BC、AB长为半径画弧,两弧交于点D,AD=BC,AB=CD。四边形ABCD 是平行四边形(两组对边分别相等的四边形
5、是平行四边形)。故选 A。5.(2012四川广元 3 分)若以 A(-0.5,0),B(2,0),C(0,1)三点为顶点要画平行四边形,则第四个顶点不可能在【】A.第一象限 B.第二象限 C.第三象限 D.第四象限文档编码:CK7A7D8P4Z10 HU7N7X4O7N1 ZK3R7P7L7K3文档编码:CK7A7D8P4Z10 HU7N7X4O7N1 ZK3R7P7L7K3文档编码:CK7A7D8P4Z10 HU7N7X4O7N1 ZK3R7P7L7K3文档编码:CK7A7D8P4Z10 HU7N7X4O7N1 ZK3R7P7L7K3文档编码:CK7A7D8P4Z10 HU7N7X4O7N1
6、 ZK3R7P7L7K3文档编码:CK7A7D8P4Z10 HU7N7X4O7N1 ZK3R7P7L7K3文档编码:CK7A7D8P4Z10 HU7N7X4O7N1 ZK3R7P7L7K3文档编码:CK7A7D8P4Z10 HU7N7X4O7N1 ZK3R7P7L7K3文档编码:CK7A7D8P4Z10 HU7N7X4O7N1 ZK3R7P7L7K3文档编码:CK7A7D8P4Z10 HU7N7X4O7N1 ZK3R7P7L7K3文档编码:CK7A7D8P4Z10 HU7N7X4O7N1 ZK3R7P7L7K3文档编码:CK7A7D8P4Z10 HU7N7X4O7N1 ZK3R7P7L7K3文
7、档编码:CK7A7D8P4Z10 HU7N7X4O7N1 ZK3R7P7L7K3文档编码:CK7A7D8P4Z10 HU7N7X4O7N1 ZK3R7P7L7K3文档编码:CK7A7D8P4Z10 HU7N7X4O7N1 ZK3R7P7L7K3文档编码:CK7A7D8P4Z10 HU7N7X4O7N1 ZK3R7P7L7K3文档编码:CK7A7D8P4Z10 HU7N7X4O7N1 ZK3R7P7L7K3文档编码:CK7A7D8P4Z10 HU7N7X4O7N1 ZK3R7P7L7K3文档编码:CK7A7D8P4Z10 HU7N7X4O7N1 ZK3R7P7L7K3文档编码:CK7A7D8P4
8、Z10 HU7N7X4O7N1 ZK3R7P7L7K3文档编码:CK7A7D8P4Z10 HU7N7X4O7N1 ZK3R7P7L7K3文档编码:CK7A7D8P4Z10 HU7N7X4O7N1 ZK3R7P7L7K3文档编码:CK7A7D8P4Z10 HU7N7X4O7N1 ZK3R7P7L7K3文档编码:CK7A7D8P4Z10 HU7N7X4O7N1 ZK3R7P7L7K3文档编码:CK7A7D8P4Z10 HU7N7X4O7N1 ZK3R7P7L7K3文档编码:CK7A7D8P4Z10 HU7N7X4O7N1 ZK3R7P7L7K3文档编码:CK7A7D8P4Z10 HU7N7X4O7
9、N1 ZK3R7P7L7K3文档编码:CK7A7D8P4Z10 HU7N7X4O7N1 ZK3R7P7L7K3文档编码:CK7A7D8P4Z10 HU7N7X4O7N1 ZK3R7P7L7K3文档编码:CK7A7D8P4Z10 HU7N7X4O7N1 ZK3R7P7L7K3文档编码:CK7A7D8P4Z10 HU7N7X4O7N1 ZK3R7P7L7K3文档编码:CK7A7D8P4Z10 HU7N7X4O7N1 ZK3R7P7L7K3文档编码:CK7A7D8P4Z10 HU7N7X4O7N1 ZK3R7P7L7K3文档编码:CK7A7D8P4Z10 HU7N7X4O7N1 ZK3R7P7L7K
10、3文档编码:CK7A7D8P4Z10 HU7N7X4O7N1 ZK3R7P7L7K3文档编码:CK7A7D8P4Z10 HU7N7X4O7N1 ZK3R7P7L7K3文档编码:CK7A7D8P4Z10 HU7N7X4O7N1 ZK3R7P7L7K3文档编码:CK7A7D8P4Z10 HU7N7X4O7N1 ZK3R7P7L7K3文档编码:CK7A7D8P4Z10 HU7N7X4O7N1 ZK3R7P7L7K3文档编码:CK7A7D8P4Z10 HU7N7X4O7N1 ZK3R7P7L7K3文档编码:CK7A7D8P4Z10 HU7N7X4O7N1 ZK3R7P7L7K3文档编码:CK7A7D8
11、P4Z10 HU7N7X4O7N1 ZK3R7P7L7K3文档编码:CK7A7D8P4Z10 HU7N7X4O7N1 ZK3R7P7L7K3文档编码:CK7A7D8P4Z10 HU7N7X4O7N1 ZK3R7P7L7K3文档编码:CK7A7D8P4Z10 HU7N7X4O7N1 ZK3R7P7L7K3文档编码:CK7A7D8P4Z10 HU7N7X4O7N1 ZK3R7P7L7K3文档编码:CK7A7D8P4Z10 HU7N7X4O7N1 ZK3R7P7L7K3文档编码:CK7A7D8P4Z10 HU7N7X4O7N1 ZK3R7P7L7K3精心整理【答案】C。【考点】平行四边形的判定,坐标
12、与图形性质。【分析】根据题意画出图形,如图所示:分三种情况考虑:以 CB 为对角线作平行四边形ABD1C,此时第四个顶点D1落在第一象限;以 AC为对角线作平行四边形ABCD2,此时第四个顶点D2落在第二象限;以 AB为对角线作平行四边形ACBD3,此时第四个顶点D3落在第四象限。则第四个顶点不可能落在第三象限。故选C。6.(2012 四川德阳 3 分)如图,点 D是ABC的边 AB的延长线上一点,点F 是边 BC上的一个动点(不与点 B重合).以 BD、BF为邻边作平行四边形BDEF,又 APBE(点 P、E在直线 AB的同侧),如果BDB14A,那么 PBC 的面积与 ABC面积之比为【】
13、A.41B.53C.51D.43【答案】D。【考点】平行四边形的判定和性质。【分析】过点 P作 PH BC交 AB于 H,连接 CH,PF,PE。APBE,四边形 APEB 是平行四边形。PEAB。,四边形BDEF是平行四边形,EFBD。EF AB。P,E,F 共线。设 BD=a,1BDAB4,PE=AB=4a。PF=PE EF=3a。PH BC,SHBC=SPBC。PF AB,四边形BFPH是平行四边形。BH=PF=3a。SHBC:SABC=BH:AB=3a:4a=3:4,SPBC:SABC=3:4。故选 D。7.(2012四川巴中 3 分)不能判定一个四边形是平行四边形的条件是【】A.两组
14、对边分别平行B.一组对边平行,另一组对边相等C.一组对边平行且相等D.两组对边分别相等【答案】B。文档编码:CV3T3J3X1G5 HV3S6X3N7P7 ZK2X6Y4I1F5文档编码:CV3T3J3X1G5 HV3S6X3N7P7 ZK2X6Y4I1F5文档编码:CV3T3J3X1G5 HV3S6X3N7P7 ZK2X6Y4I1F5文档编码:CV3T3J3X1G5 HV3S6X3N7P7 ZK2X6Y4I1F5文档编码:CV3T3J3X1G5 HV3S6X3N7P7 ZK2X6Y4I1F5文档编码:CV3T3J3X1G5 HV3S6X3N7P7 ZK2X6Y4I1F5文档编码:CV3T3J
15、3X1G5 HV3S6X3N7P7 ZK2X6Y4I1F5文档编码:CV3T3J3X1G5 HV3S6X3N7P7 ZK2X6Y4I1F5文档编码:CV3T3J3X1G5 HV3S6X3N7P7 ZK2X6Y4I1F5文档编码:CV3T3J3X1G5 HV3S6X3N7P7 ZK2X6Y4I1F5文档编码:CV3T3J3X1G5 HV3S6X3N7P7 ZK2X6Y4I1F5文档编码:CV3T3J3X1G5 HV3S6X3N7P7 ZK2X6Y4I1F5文档编码:CV3T3J3X1G5 HV3S6X3N7P7 ZK2X6Y4I1F5文档编码:CV3T3J3X1G5 HV3S6X3N7P7 ZK
16、2X6Y4I1F5文档编码:CV3T3J3X1G5 HV3S6X3N7P7 ZK2X6Y4I1F5文档编码:CV3T3J3X1G5 HV3S6X3N7P7 ZK2X6Y4I1F5文档编码:CV3T3J3X1G5 HV3S6X3N7P7 ZK2X6Y4I1F5文档编码:CV3T3J3X1G5 HV3S6X3N7P7 ZK2X6Y4I1F5文档编码:CV3T3J3X1G5 HV3S6X3N7P7 ZK2X6Y4I1F5文档编码:CV3T3J3X1G5 HV3S6X3N7P7 ZK2X6Y4I1F5文档编码:CV3T3J3X1G5 HV3S6X3N7P7 ZK2X6Y4I1F5文档编码:CV3T3J
17、3X1G5 HV3S6X3N7P7 ZK2X6Y4I1F5文档编码:CV3T3J3X1G5 HV3S6X3N7P7 ZK2X6Y4I1F5文档编码:CV3T3J3X1G5 HV3S6X3N7P7 ZK2X6Y4I1F5文档编码:CV3T3J3X1G5 HV3S6X3N7P7 ZK2X6Y4I1F5文档编码:CV3T3J3X1G5 HV3S6X3N7P7 ZK2X6Y4I1F5文档编码:CV3T3J3X1G5 HV3S6X3N7P7 ZK2X6Y4I1F5文档编码:CV3T3J3X1G5 HV3S6X3N7P7 ZK2X6Y4I1F5文档编码:CV3T3J3X1G5 HV3S6X3N7P7 ZK
18、2X6Y4I1F5文档编码:CV3T3J3X1G5 HV3S6X3N7P7 ZK2X6Y4I1F5文档编码:CV3T3J3X1G5 HV3S6X3N7P7 ZK2X6Y4I1F5文档编码:CV3T3J3X1G5 HV3S6X3N7P7 ZK2X6Y4I1F5文档编码:CV3T3J3X1G5 HV3S6X3N7P7 ZK2X6Y4I1F5文档编码:CV3T3J3X1G5 HV3S6X3N7P7 ZK2X6Y4I1F5文档编码:CV3T3J3X1G5 HV3S6X3N7P7 ZK2X6Y4I1F5文档编码:CV3T3J3X1G5 HV3S6X3N7P7 ZK2X6Y4I1F5文档编码:CV3T3J
19、3X1G5 HV3S6X3N7P7 ZK2X6Y4I1F5文档编码:CV3T3J3X1G5 HV3S6X3N7P7 ZK2X6Y4I1F5文档编码:CV3T3J3X1G5 HV3S6X3N7P7 ZK2X6Y4I1F5文档编码:CV3T3J3X1G5 HV3S6X3N7P7 ZK2X6Y4I1F5文档编码:CV3T3J3X1G5 HV3S6X3N7P7 ZK2X6Y4I1F5文档编码:CV3T3J3X1G5 HV3S6X3N7P7 ZK2X6Y4I1F5文档编码:CV3T3J3X1G5 HV3S6X3N7P7 ZK2X6Y4I1F5文档编码:CV3T3J3X1G5 HV3S6X3N7P7 ZK
20、2X6Y4I1F5文档编码:CV3T3J3X1G5 HV3S6X3N7P7 ZK2X6Y4I1F5文档编码:CV3T3J3X1G5 HV3S6X3N7P7 ZK2X6Y4I1F5文档编码:CV3T3J3X1G5 HV3S6X3N7P7 ZK2X6Y4I1F5文档编码:CV3T3J3X1G5 HV3S6X3N7P7 ZK2X6Y4I1F5精心整理【考点】平行四边形的判定【分析】根据平行四边形的判定:两组对边分别平行的四边形是平行四边形;两组对边分别相等的四边形是平行四边形;两组对角分别相等的四边形是平行四边形;对角线互相平分的四边形是平行四边形;一组对边平行且相等的四边形是平行四边形。A、D、C
21、均符合是平行四边形的条件,B则不能判定是平行四边形。故选B。8.(2012 四川自贡3 分)如图,在平行四边形ABCD 中,AD=5,AB=3,AE平分 BAD交 BC边于点 E,则线段BE,EC的长度分别为【】A2 和 3 B3 和 2 C4 和 1 D1 和 4【答案】B。【考点】平行四边形的性质,平行的性质,等腰三角形的判定和性质。【分析】AE平分 BAD,BAE=DAE。四边形ABCD 是平行四边形,AD BC。DAE=AEB。BAE=BEA。AB=BE=3。EC=AD BE=2。故选 B。9.(2012辽宁阜新 3 分)如图,四边形 ABCD 是平行四边形,BE平分ABC,CF平分B
22、CD,BE、CF交于点 G 若使EFD14A,那么平行四边形ABCD 应满足的条件是【】AABC=60 B AB:BC=1:4C AB:BC=5:2DAB:BC=5:8【答案】D。【考点】平行四边形的性质,平行的性质,等腰三角形的判定。【分析】四边形 ABCD 是平行四边形,AD BC,AB=CD,AD=BC。AEB=EBC。又 BE平分ABC,ABE=EBC。ABE=AEB。AB=AE。同理可得:DC=DF。AE=DF。AE EF=DE EF,即 AF=DE。当1EFAD4时,设 EF=x,则 AD=BC=4x。AF=DE=14(AD EF)=1.5x。AE=AB=AF+EF=2.5x。AB
23、:BC=2.5:4=5:8。以上各步可逆,当 AB:BC=2.5:4=5:8 时,1EFAD4。故选 D。文档编码:CV3T3J3X1G5 HV3S6X3N7P7 ZK2X6Y4I1F5文档编码:CV3T3J3X1G5 HV3S6X3N7P7 ZK2X6Y4I1F5文档编码:CV3T3J3X1G5 HV3S6X3N7P7 ZK2X6Y4I1F5文档编码:CV3T3J3X1G5 HV3S6X3N7P7 ZK2X6Y4I1F5文档编码:CV3T3J3X1G5 HV3S6X3N7P7 ZK2X6Y4I1F5文档编码:CV3T3J3X1G5 HV3S6X3N7P7 ZK2X6Y4I1F5文档编码:CV
24、3T3J3X1G5 HV3S6X3N7P7 ZK2X6Y4I1F5文档编码:CV3T3J3X1G5 HV3S6X3N7P7 ZK2X6Y4I1F5文档编码:CV3T3J3X1G5 HV3S6X3N7P7 ZK2X6Y4I1F5文档编码:CV3T3J3X1G5 HV3S6X3N7P7 ZK2X6Y4I1F5文档编码:CV3T3J3X1G5 HV3S6X3N7P7 ZK2X6Y4I1F5文档编码:CV3T3J3X1G5 HV3S6X3N7P7 ZK2X6Y4I1F5文档编码:CV3T3J3X1G5 HV3S6X3N7P7 ZK2X6Y4I1F5文档编码:CV3T3J3X1G5 HV3S6X3N7P
25、7 ZK2X6Y4I1F5文档编码:CV3T3J3X1G5 HV3S6X3N7P7 ZK2X6Y4I1F5文档编码:CV3T3J3X1G5 HV3S6X3N7P7 ZK2X6Y4I1F5文档编码:CV3T3J3X1G5 HV3S6X3N7P7 ZK2X6Y4I1F5文档编码:CV3T3J3X1G5 HV3S6X3N7P7 ZK2X6Y4I1F5文档编码:CV3T3J3X1G5 HV3S6X3N7P7 ZK2X6Y4I1F5文档编码:CV3T3J3X1G5 HV3S6X3N7P7 ZK2X6Y4I1F5文档编码:CV3T3J3X1G5 HV3S6X3N7P7 ZK2X6Y4I1F5文档编码:CV
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