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1、七年级下册数学几何复习题_112(如图所示，在?ABC中，?A,80?，?B,30?，CD平分?ACB，DE?AC. (1)求?DEB的度数; (2)求?EDC的度数( 解 (1)在?ABC中，?A,80?，?B,30?， ?ACB,180?,?A,?B,70?. ?DE?AC， ?DEB,?ACB,70?. (2)?CD平分?ACB， 1?DCE,?ACB,35?. 2?DEB,?DCE，?EDC， ?EDC,70?,35?,35?. 13(已知，如图，?1,?2，CF?AB于F，DE?AB于E，求证:FG?BC.(请将证明补充完整) 证明 ?CF?AB，DE?AB(已知)， ?ED?FC(
2、 )( ?1,?BCF( )( 又?1,?2(已知)， ?2,?BCF(等量代换)， ?FG?BC( )( 解 在同一平面内，垂直于同一直线的两条直线互相平行;两直线平行，同位角相等;内错角相等，两直线平行( 14(如图，已知三角形ABC，求证:?A，?B，?C,180?. 分析:通过画平行线，将?A、?B、?C作等角代换，使各角之和恰为一平角，依辅助线不同而得多种证法，如下: 证法1:如图甲，延长BC到D，过C画CE?BA. ?BA?CE(作图所知)， urban area 2.5.2 Yibin city in Yibin city, according to resource and e
3、nvironment characteristics Urban population and urban spatial distribution, spatial distribution of industries, major infrastructure Corridor layout, combined with the future development trend of synthetic judgments, planning, urban spatial structure of urban system can be summarized as: a pole alon
4、g the two axes. A refers to the metropolitan area along the Yangtze River, is the core area of the development of the city. Plans to build for the Yangtze River economic belt on the pillar, advancing along the . Guanghe River, Yiliang, prestige of the external cohesion of zhaotong, Yunnan, internal
5、connecting Yibin city to the North. The Sichuan-Yunnan-Guizhou border area of Yibin, in the city of zhaotong, liupanshui three, zhaotong city, the most populous and most extensive regions, the most economically backward, to the North in Wumeng mountain area of yanjin, shuifu, suijiang counties radia
6、tion power is relatively weak. Yibin city and infrastructure in such areas should be strengthened and docking, extending southward to public services, promote the development of mineral resources in Northeast Yunnan, expand our economic hinterland, driving synchronous lifting in Sichuan-Yunnan-Guizh
7、ou border area. This urban axis with mineral resource advantages, focus on the development of advanced technology, comprehensive utilization of resources of higher energy, new building materials, chemical industry, developing new energy and mining towns. Urban space organization-in gongxian County,
8、Gao, junlian County Center for area organizations, improve, Gao, Gong, junlian County comprehensive services, and promoting regional economic development and population growth of the agglomeration. Along the main traffic arteries to implement point-axis development mode key repeatedly, Shahe town, X
9、iao Zhen, Luo table Zhen, Luo town, love Mu Zhen and other towns as district development focuses on cities and towns, promote the development of district ?B,?1，?A,?2(两直线平行，同位角、内错角相等)( 又?BCD,?BCA，?2，?1,180?(平角的定义)， ?A，?B，?ACB,180?(等量代换)( 如图乙，过BC上任一点F，画FH?AC，FG?AB，这种添加辅助线的方法能证明?A，?B，?C,180?吗,请你试一试( 解
10、?FH?AC， ?BHF,?A，?1,?C. ?FG?AB， ?BHF,?2，?3,?B， ?2,?A. ?BFC,180?， ?1，?2，?3,180?， ?，?，?,180?. 即ABC15(2010?玉溪)平面内的两条直线有相交和平行两种位置关系( (1)如图a，若AB?CD，点P在AB、CD外部，则有?B,?BOD.又因?BOD是?POD的外角，故?BOD,?BPD，?D，得?BPD,?B,?D.将点P移到AB、CD内部，如图b，以上结论是否成立,若成立，说明理由;若不成立，则?BPD、?B、?D之间有何数量关系,请证明你的结论; (2)在图b中，将直线AB绕点B逆时针方向旋转一定角度
11、交直线CD于点Q，如图c，则?BPD、?B、?D、?BQD之间有何数量关系,(不需证明) (3)根据(2)的结论求图d中?A，?B，?C，?D，?E，?F的度数( 解 (1)不成立，结论是?BPD,?B，?D. 延长BP交CD于点E， is relatively weak. Yibin city and infrastructure in such areas should be strengthened and docking, extending southward to pu powerregions, the most economically backward, to the Nor
12、th in Wumeng mountain area of yanjin, shuifu, suijiang counties radiation Guizhou border area of Yibin, in the city of zhaotong, liupanshui three, zhaotong city, the most populous and most extensive -Yunnan-er, Yiliang, prestige of the external cohesion of zhaotong, Yunnan, internal connecting Yibin
13、 city to the North. The Sichuanevelopment of the city. Plans to build for the Yangtze River economic belt on the pillar, advancing along the . Guanghe Rivthe dsummarized as: a pole along the two axes. A refers to the metropolitan area along the Yangtze River, is the core area of , combined with the
14、future development trend of synthetic judgments, planning, urban spatial structure of urban system can bepatial distribution, spatial distribution of industries, major infrastructure Corridor layouturban area 2.5.2 Yibin city in Yibin city, according to resource and environment characteristics Urban
15、 population and urban s2velopment of districtict development focuses on cities and towns, promote the deaxis development mode key repeatedly, Shahe town, Xiao Zhen, Luo table Zhen, Luo town, love Mu Zhen and other towns as distr-the agglomeration. Along the main traffic arteries to implement point c
16、es, and promoting regional economic development and population growth ofin gongxian County, Gao, junlian County Center for area organizations, improve, Gao, Gong, junlian County comprehensive servi-ing new energy and mining towns. Urban space organizationehensive utilization of resources of higher e
17、nergy, new building materials, chemical industry, developGuizhou border area. This urban axis with mineral resource advantages, focus on the development of advanced technology, compr-Yunnan-us lifting in Sichuanhronoblic services, promote the development of mineral resources in Northeast Yunnan, exp
18、and our economic hinterland, driving sync ?AB?CD，?B,?BED. 又?BPD,?BED，?D， ?BPD,?B，?D. (2)结论:?BPD,?BQD，?B，?D. (3)设AC与BF交于点G. 由(2)的结论得:?AGB,?A，?B，?E. 又?AGB,?CGF，?CGF，?C，?D，?F,360?，?A，?B，?C，?D，?E，?F,360?. AD14(把一副常用的三角板如图所示拼在一起，那么图中?ADE是 度( E CB第14题 2(如图，在?ABC和?ABD中，现给出如下三个论断:?AD,BC;?C,?D;?1,?2。请选择其中两个论
19、断为条件，一个论断为结论，另外构造一个命题( ?,?(1)写出所有的正确命题(写成“ ”形式，用序号表示):( ,?,(2)请选择一个正确的命题加以说明(你选择的正确命题是: ,说明: 3(如图，直线AD和BC相交于O，AB?CD，?AOC,95?，?B,50?，求?A和?D. 4(如图，?ABC中，角平分线AD、BE、CF相交于点H，过H点作HG?AB，垂足为G，那么?AHE,?CHG吗,为什么, in gongxian County, Gao, junlian County Center for area organizations, improve, Gao, Gong, junlian
20、 County comprehensive servi-ew energy and mining towns. Urban space organizationehensive utilization of resources of higher energy, new building materials, chemical industry, developing nGuizhou border area. This urban axis with mineral resource advantages, focus on the development of advanced techn
21、ology, compr-Yunnan-fting in Sichuanus liservices, promote the development of mineral resources in Northeast Yunnan, expand our economic hinterland, driving synchrono elatively weak. Yibin city and infrastructure in such areas should be strengthened and docking, extending southward to publicr is ron
22、s, the most economically backward, to the North in Wumeng mountain area of yanjin, shuifu, suijiang counties radiation powehou border area of Yibin, in the city of zhaotong, liupanshui three, zhaotong city, the most populous and most extensive regiGuiz-Yunnan-iliang, prestige of the external cohesio
23、n of zhaotong, Yunnan, internal connecting Yibin city to the North. The Sichuanpment of the city. Plans to build for the Yangtze River economic belt on the pillar, advancing along the . Guanghe River, Ydeveloarized as: a pole along the two axes. A refers to the metropolitan area along the Yangtze Ri
24、ver, is the core area of the bined with the future development trend of synthetic judgments, planning, urban spatial structure of urban system can be summpatial distribution, spatial distribution of industries, major infrastructure Corridor layout, comurban area 2.5.2 Yibin city in Yibin city, accor
25、ding to resource and environment characteristics Urban population and urban s3ment of districtict development focuses on cities and towns, promote the developaxis development mode key repeatedly, Shahe town, Xiao Zhen, Luo table Zhen, Luo town, love Mu Zhen and other towns as distr-agglomeration. Al
26、ong the main traffic arteries to implement pointces, and promoting regional economic development and population growth of the 5(如图17，在?ABC中，AD为?BAC的平分线，DE?AB于E，DF?AC于F，?ABC面积2是，AB=20厘米，AC=8厘米，求DE的长( 28cm第5题 6(如图，已知AB?CD，垂足为B，AB=DB，AC=DE(请你判断?D与?A的关系，并说明理由( A E CBD第6题 7(如图，AD=BC，DC=AB，AE=CF，找出图中的一对全等
27、三角形，并说明你的理由( DC FEBA 第7题 8(如图，已知M在AB上，BC=BD，MC=MD(请说明:AC=AD( C M BA第8题 Dus lifting in Sichuanhronoblic services, promote the development of mineral resources in Northeast Yunnan, expand our economic hinterland, driving syncis relatively weak. Yibin city and infrastructure in such areas should be str
28、engthened and docking, extending southward to pu powerregions, the most economically backward, to the North in Wumeng mountain area of yanjin, shuifu, suijiang counties radiation Guizhou border area of Yibin, in the city of zhaotong, liupanshui three, zhaotong city, the most populous and most extens
29、ive -Yunnan-er, Yiliang, prestige of the external cohesion of zhaotong, Yunnan, internal connecting Yibin city to the North. The Sichuanevelopment of the city. Plans to build for the Yangtze River economic belt on the pillar, advancing along the . Guanghe Rivthe dsummarized as: a pole along the two
30、axes. A refers to the metropolitan area along the Yangtze River, is the core area of , combined with the future development trend of synthetic judgments, planning, urban spatial structure of urban system can bepatial distribution, spatial distribution of industries, major infrastructure Corridor lay
31、outurban area 2.5.2 Yibin city in Yibin city, according to resource and environment characteristics Urban population and urban s4velopment of districtict development focuses on cities and towns, promote the deaxis development mode key repeatedly, Shahe town, Xiao Zhen, Luo table Zhen, Luo town, love
32、 Mu Zhen and other towns as distr-the agglomeration. Along the main traffic arteries to implement point ces, and promoting regional economic development and population growth ofin gongxian County, Gao, junlian County Center for area organizations, improve, Gao, Gong, junlian County comprehensive ser
33、vi-ing new energy and mining towns. Urban space organizationehensive utilization of resources of higher energy, new building materials, chemical industry, developGuizhou border area. This urban axis with mineral resource advantages, focus on the development of advanced technology, compr-Yunnan- 9(如图
34、， 在?ABC中，AB=AC，AC边上中线BD把?ABC的周长分为21厘米 12厘米两部分，求?ABC各边的长. A D B C 10(已知AE?BD，CF?BD，且AD=BC，BE=DF，试判断AD和BC的位置关系.说明你的结论( 11(如图，?ACB=?BDA=90?，AD=BC，AB/CD(试说明:?1=?2( 12(如图,，AC?BD，AC=DC，CB=CE，试说明:DE?AB( 13(如图，已知AB/DE，AB=DE，BE=CF，试说明?ABC?DEF的理由. 小明的说理过程如下: 因为AB/DE，所以?1=?2， 在?ABC和?DEF中 因为BE=CF，?1=?2，AB=DE，所以
35、?ABC?DEF(SAS). 小明的说理正确吗,若不正确，请你指出错误，帮助小明走出说理误区. 14(如图2，AC与BD相交于点E，AD=BC，?D=?C，试说明AC与BD全等的理由. Guizhou border area. This urban axis with mineral resource advantages, focus on the development of advanced technology, compr-Yunnan-fting in Sichuanus liservices, promote the development of mineral resource
36、s in Northeast Yunnan, expand our economic hinterland, driving synchrono elatively weak. Yibin city and infrastructure in such areas should be strengthened and docking, extending southward to publicr is rons, the most economically backward, to the North in Wumeng mountain area of yanjin, shuifu, sui
37、jiang counties radiation powehou border area of Yibin, in the city of zhaotong, liupanshui three, zhaotong city, the most populous and most extensive regiGuiz-Yunnan-iliang, prestige of the external cohesion of zhaotong, Yunnan, internal connecting Yibin city to the North. The Sichuanpment of the ci
38、ty. Plans to build for the Yangtze River economic belt on the pillar, advancing along the . Guanghe River, Ydeveloarized as: a pole along the two axes. A refers to the metropolitan area along the Yangtze River, is the core area of the bined with the future development trend of synthetic judgments, p
39、lanning, urban spatial structure of urban system can be summpatial distribution, spatial distribution of industries, major infrastructure Corridor layout, comurban area 2.5.2 Yibin city in Yibin city, according to resource and environment characteristics Urban population and urban s5ment of district
40、ict development focuses on cities and towns, promote the developaxis development mode key repeatedly, Shahe town, Xiao Zhen, Luo table Zhen, Luo town, love Mu Zhen and other towns as distr-agglomeration. Along the main traffic arteries to implement pointces, and promoting regional economic developme
41、nt and population growth of the in gongxian County, Gao, junlian County Center for area organizations, improve, Gao, Gong, junlian County comprehensive servi-ew energy and mining towns. Urban space organizationehensive utilization of resources of higher energy, new building materials, chemical indus
42、try, developing n 小华的说理过程如下: 在?ABD和?BAC中， 因为AD=BC，AB=BA，?C=?D， 所以?ABD?BAC(SSA) 所以AC=BD. 3(10分)如图15，在?ABC中，点D在AB上，BD=BE， (1)请你再添加一个条件，使得?BEA?BDC， 并说明理由，你添加的条件是 理由是: (2)根据你添加的条件，再写出图中的一对全等三角形 (只要求写出一对全等三角形，不再添加其它线段，不再标注或使用其它字母，不必说明理由)( 4(10分)已知:如图16，Rt?ABC?Rt?ADE，?ABC, ?ADE,90?，试以图中标有的字母的点为端点，连接两条线 段，
43、如图你所连接的两条线段满足相等、垂直或平行关系中的 一种，那么请你把它写出来并证明( 1. 现有两根棍子长分别为3厘米，5厘米，若要选第三根棍子，使其与前两根拼成一个三角形，则它的长可为( ) A.1厘米 B.2厘米 C.5厘米 D.10厘米 A B E D C 图1 图2 2.如图1所示，AD是?ABC的高，延长BC至E，使CE,BC，?ABC的面积为S，?ACE1-Yunnan-us lifting in Sichuanhronoblic services, promote the development of mineral resources in Northeast Yunnan,
44、expand our economic hinterland, driving syncis relatively weak. Yibin city and infrastructure in such areas should be strengthened and docking, extending southward to pu powerregions, the most economically backward, to the North in Wumeng mountain area of yanjin, shuifu, suijiang counties radiation
45、Guizhou border area of Yibin, in the city of zhaotong, liupanshui three, zhaotong city, the most populous and most extensive -Yunnan-er, Yiliang, prestige of the external cohesion of zhaotong, Yunnan, internal connecting Yibin city to the North. The Sichuanevelopment of the city. Plans to build for
46、the Yangtze River economic belt on the pillar, advancing along the . Guanghe Rivthe dsummarized as: a pole along the two axes. A refers to the metropolitan area along the Yangtze River, is the core area of , combined with the future development trend of synthetic judgments, planning, urban spatial s
47、tructure of urban system can bepatial distribution, spatial distribution of industries, major infrastructure Corridor layouturban area 2.5.2 Yibin city in Yibin city, according to resource and environment characteristics Urban population and urban s6velopment of districtict development focuses on ci
48、ties and towns, promote the deaxis development mode key repeatedly, Shahe town, Xiao Zhen, Luo table Zhen, Luo town, love Mu Zhen and other towns as distr-the agglomeration. Along the main traffic arteries to implement point ces, and promoting regional economic development and population growth ofin gongxian County, Gao, junlian County Center for area organizations, improve, Gao, Gong, junlian County comprehensive servi-ing new energy and mining towns. Urban space organizationehensive utilization of resources of higher energy, new building ma