数学精英解_“圆锥曲线”题济南最大的文化课一对一辅导小班辅导机构大智学校内部资料【大智教育强烈推荐】

数学精英解_“圆锥曲线”题济南最大的文化课一对一辅导小班辅导机构大智学校内部资料【大智教育强烈推荐】 考场精彩(8) (8) 数学精英解 “圆锥曲线”题 22xy1.(2007年湖北卷第7题) 双曲线C:,,1(a>0,b>0)的左准线为l,左焦点和右焦122ab 点分别为F和F;抛物线C的准线为l，焦点为F.C和C的一个交点为M，则122212|FF||MF|121等于 ,|MF||MF|12 11A.-1 B.1 C. D. ,22 解答: 设双曲线的离心离为e,如图: |FF||MF|2ce|MN|2ae121,= ,,,e|MF||MF||MF||MN|e|MF|1112 |MF|,|MF||MN|12 ,e,,e,e(1,),e,e,1,e,,1|MF|e|MN|1 为A. 【说明】MN是转换的中介，巧用定义. 22xyab,,0，,12.(湖南卷第9题) 设分别是椭圆()的左、右焦点，若在其右FF，1222ab 准线上存在使线段PF的中垂线过点F，则椭圆离心率的取值范围是( ) P,12 ,，,，，,，,2323A( B( C( D( 0，，10，，1,,,,,,,,,,,,2233,，，,,，，, 22,,aaxFcFcPyPF,,,,0,,0,,,F,解: 椭圆的右准线方程为的中垂线过则，，，，,,1212cc,, 224,,aa2222,,， FF,FP,？2c,,c，y,y,3c，2a,1222,,cc,, 13322当y,0时，最少，即:故选D. 3201.eee,，,,,,,,y2e33答案为D. 【说明】 充分利用圆锥曲线的性质寻找解题的突破口. 2(40),，(40)，3.(全国卷?第4题) 已知双曲线的离心率为，焦点是，，则双曲线方程为 the provisions of Hunan province safety production supervision and management responsibilities > (Hunan Zhengban made 2013 No. 4), resolutely implement the safety production of the party with responsibility, a pair of responsibility. "Two is issued safety production administration and inspection to promote the responsibilities bear safety production supervision departments strictly and effectively assumed responsibility. The three is the establishment of enterprise production safety hidden With self correction self reporting system, promote the enterprises to implement the main responsibility for production safety. The four is the introduction of strengthening county safety production supervision ability construction work, promote safe production responsibility to the grassroots. 3, strict accountability and target management. Adhere to the "who is in charge, who is responsible for the pipe industry must pipes, pipe production and management must control safety management business must be safe" principle, the implementation of safe production supervision and stagnation to cure. "The leadership responsible system. Production safety of key towns, key enterprises and key problems, by the township government and the Department responsible for the stagnation led the lump sum, to tackle tough. To further increase the production safety index assessment, strict implementation of safe production of "one vote veto" award and recognition system, strengthen production safety incentive mechanism (four). Adhere to the political principles against unwholesome tendencies existence of the problem is not strict internal supervision. Over the years, the global leadership team members do not have any illegal and other bad records, but there are still not strict, the implementation does not survive the problem. A few leading cadres not strictly in accordance with the county Party committee, county government On strengthening style construction requirements and style construction safety supervision system of "ten prohibitions", to solve the people most concerned, the most direct, the most realistic problem of production safety as the starting point and goal of all work, to strengthen internal supervision on the way, in the perfect power control mechanism on "let things drift", get free in the political norms of leading cadres, some involving major principle problems of ambiguous attitude, major issues issues of right and wrong, it cannot stand up bravely, face to face, resolute struggle and discredit the views of the party in 2012. The style of the big consolidation activities, cadres and workers 6 people were ( ) 22222222xyxyxyxyA( B( C( D( ,,1,,1,,1,,1412124106610 解答:c=4，e=2，则a=2.焦点在x轴上.答案为A. c222【说明】 e,,a，b,c.a 2l4.(全国卷?第11题) 抛物线的焦点为F，准线为，经过F且斜率为3的直线与yx,4 AKl??AKF抛物线在轴上方的部分相交于点A，，垂足为K，则的面积是( ) x 8A( B(33 C(43 D( 4 2,y,4x,解答: ,|AK|=3-(-1)=4， 联立,A(3,23),,y,3(x,1), 1S,，4，23,43. ,ABC2 答案为C. 【说明】 A点是突破点，只要求出它，便迎刃而解. 5.(浙江卷第4题) 要在边长为16米的正方形草坪上安装喷水龙头，使整个草坪都能喷洒到 水(假设每个喷水龙头的喷洒范围都是半径为6米的圆面，则需安装这种喷水龙头的个数最 少是( ) 3564,( ,( ,( ,( 解答:每一条边上至少得2个，则对称性知，最少得安装4个. 【而答】 答案为B. 22xyP,,,,1(00)ab，6.(浙江卷第9题) 已知双曲线的左、右焦点分别为F，F，是1222ab PFPFab ,4准线上一点，且PFPF,，，则双曲线的离心率是( ) 1212 3322,( ,( ,( ,( 解答: ?PF,PF,?. PF,PF,01212 44222,,,,,,ca,aaa,,,,,,yP,y,c,,,y,c,,,y,0||,设,则解得, ,,,,,,cccc,,,,,, 11S,|PF||PF|,2ab及S,|FF|,|y|,2ab又由 ,PFF12,PFF12121222 441c,a，2c，,2ab,解得c,3a,？e,3.得 2c e perfect power control mechanism on "let things drift", get free in the political norms of leading cadres, some involving maproblem of production safety as the starting point and goal of all work, to strengthen internal supervision on the way, in th listicnstruction safety supervision system of "ten prohibitions", to solve the people most concerned, the most direct, the most rean accordance with the county Party committee, county government On strengthening style construction requirements and style coctly ir bad records, but there are still not strict, the implementation does not survive the problem. A few leading cadres not strioblem is not strict internal supervision. Over the years, the global leadership team members do not have any illegal and othethe prproduction safety incentive mechanism (four). Adhere to the political principles against unwholesome tendencies existence of afety index assessment, strict implementation of safe production of "one vote veto" award and recognition system, strengthen tion sovernment and the Department responsible for the stagnation led the lump sum, to tackle tough. To further increase the produccure. "The leadership responsible system. Production safety of key towns, key enterprises and key problems, by the township gon to st control safety management business must be safe" principle, the implementation of safe production supervision and stagnatiment. Adhere to the "who is in charge, who is responsible for the pipe industry must pipes, pipe production and management mumanageion ability construction work, promote safe production responsibility to the grassroots. 3, strict accountability and target he main responsibility for production safety. The four is the introduction of strengthening county safety production supervisment tblishment of enterprise production safety hidden With self correction self reporting system, promote the enterprises to impleilities bear safety production supervision departments strictly and effectively assumed responsibility. The three is the estaponsibh responsibility, a pair of responsibility. "Two is issued safety production administration and inspection to promote the resd management responsibilities > (Hunan Zhengban made 2013 No. 4), resolutely implement the safety production of the party witthe provisions of Hunan province safety production supervision aneople werers 6 psolute struggle and discredit the views of the party in 2012. The style of the big consolidation activities, cadres and workerinciple problems of ambiguous attitude, major issues issues of right and wrong, it cannot stand up bravely, face to face, rejor p- 2 - 山东省最大的中小学课外辅导 www.dz211.com 答案为B. 【说明】 用向量解决解析几何. 7.(江苏卷第3题) 在平面直角坐标系中，双曲线的中心在坐标原点，焦点在轴上，yxOy 一条渐近线的方程为，则它的离心率为( ) xy,,20 5,(5 ,( ,(3 ,(2 2 21ab,,2,,e,1，,1，2,5解答:渐近线的斜率. ,,2ba,, 答案为A. 222ca，bb,,e,,,1，【说明】 离心率. ,,2aaa,, 22xy,,18.(全国卷?第11题) 设F，F分别是双曲线的左、右焦点。若双曲线上存在1222ab 点A，使?FAF=90º，且|AF|=3|AF|，则双曲线离心率为 1212 510155(A) (B) (C) (D) 222 2220，,,，,FAFAFAFFF90FFc,2解答:由题设知，将|AF|=3|AF|以及代1212121212 31010入后解得， AFcAFc,,,1255 3101010c又由双曲线定义知 ccae,,,,,2552a 答案为B. 【说明】 本题除了将题设部分看错以外，不会出现选错情况，比如将条件|AF|=3|AF|看错12为|AF|=2|AF|，就可能选错为A等. 12 29.(全国卷?第12题) 设F为抛物线y=4x的焦点，A、B、C为该抛物线上三点，若FA，FB，FC=0，则|FA|+|FB|+|FC|= (A)9 (B) 6 (C) 4 (D) 3 解答: 欲求|FA|+|FB|+|FC|，根据抛物线的定义，只需求A、B、C三点的横坐标之和即可。 he party in 2012. The style of the big consolidation activities, cadres and workers 6 people weres of te, major issues issues of right and wrong, it cannot stand up bravely, face to face, resolute struggle and discredit the viewhings drift", get free in the political norms of leading cadres, some involving major principle problems of ambiguous attitudlet tarting point and goal of all work, to strengthen internal supervision on the way, in the perfect power control mechanism on "prohibitions", to solve the people most concerned, the most direct, the most realistic problem of production safety as the st f "ten mittee, county government On strengthening style construction requirements and style construction safety supervision system ot, the implementation does not survive the problem. A few leading cadres not strictly in accordance with the county Party comstric on. Over the years, the global leadership team members do not have any illegal and other bad records, but there are still not. Adhere to the political principles against unwholesome tendencies existence of the problem is not strict internal supervisifour)tation of safe production of "one vote veto" award and recognition system, strengthen production safety incentive mechanism (the stagnation led the lump sum, to tackle tough. To further increase the production safety index assessment, strict implemensafety. The four is the introduction of strengthening county safety production supervision ability construction work, promote le forem. Production safety of key towns, key enterprises and key problems, by the township government and the Department responsibe safe" principle, the implementation of safe production supervision and stagnation to cure. "The leadership responsible systust bwho is responsible for the pipe industry must pipes, pipe production and management must control safety management business m production responsibility to the grassroots. 3, strict accountability and target management. Adhere to the "who is in charge,safe dden With self correction self reporting system, promote the enterprises to implement the main responsibility for production ety hision departments strictly and effectively assumed responsibility. The three is the establishment of enterprise production saf"Two is issued safety production administration and inspection to promote the responsibilities bear safety production supervi. 4), resolutely implement the safety production of the party with responsibility, a pair of responsibility. the provisions of Hunan province safety production supervision and management responsibilities > (Hunan Zhengban made 2013 No-- 3 3 -- - 3 - 提分热线: 提分太快 请系好安全带～ 中高考热门资料库(免费下载): 2设抛物线y=4x上的三点A、B、C的坐标分别为、、 Axy(,)Bxy(,)Axy(,)112233 ,,,,,,,,2由于抛物线y=4x的焦点坐标为，所以， F(1,0)FAxy,,(1,)FBxy,,(1,)1122,,,, ，又由=0得， FA，FB，FCxxx，，,3FCxy,,(1,)12333 进而得|FA|+|FB|+|FC|=，故选B. (1)(1)(1)336xxx，，，，，,，,123 答案为B. 【说明】 若把抛物线的焦点坐标错求为(这种错误比较容易出现)，则选错为A;F(2,0) ,,,,,,,,,,,, 0若将向量的横坐标之和错求为，则选错为D。 FAFBFC、、 22xy310.(天津卷第4题)设双曲线的离心率为，且它的一条准线与,,,,1(00)ab，22ab 2抛物线的准线重合，则此双曲线的方程为( ) yx,4 2222xyxy,,1,,1,( ,( 48961224 2222xyxy2,,1,,1,( ,( 3336 22caa解答: e,3,,？c,3a.而,,,1,？,1.？a,3,c,3.acc 答案为D. 【说明】 离心率连着a和c,而求出了它们，b就知道了. 2y2x,,111.(辽宁卷第11题) 设P为又曲线上的一点，F、F是该双曲线的两个焦点，若1212 |PF|?|PF|=3?2，则?PFF的面积为( ) 1212 63123A( B(12 C( D(24 解答: 由双曲线定义知|PF|-|PF|=2. 又|PF|?|PF|=3?2，解得|PF|=6，|PF|=4. 121212 2222213由双曲线方程知c=13. ?|FF|=2c=. 又?|PF|+|PF|=|FF|，?PF?PF. 12121212 11S,|PF|,|PF|,，6，4,12?. ,PFF121222 答案为B. 【说明】 本题考查双曲线的定义、性质以及基本运算能力. nstruction safety supervision system of "ten prohibitions", to solve the people most concerned, the most direct, the most rean accordance with the county Party committee, county government On strengthening style construction requirements and style coctly ir bad records, but there are still not strict, the implementation does not survive the problem. A few leading cadres not strioblem is not strict internal supervision. Over the years, the global leadership team members do not have any illegal and othethe prproduction safety incentive mechanism (four). Adhere to the political principles against unwholesome tendencies existence of afety index assessment, strict implementation of safe production of "one vote veto" award and recognition system, strengthen tion sovernment and the Department responsible for the stagnation led the lump sum, to tackle tough. To further increase the produccure. "The leadership responsible system. Production safety of key towns, key enterprises and key problems, by the township gon to st control safety management business must be safe" principle, the implementation of safe production supervision and stagnatiment. Adhere to the "who is in charge, who is responsible for the pipe industry must pipes, pipe production and management mumanageion ability construction work, promote safe production responsibility to the grassroots. 3, strict accountability and target he main responsibility for production safety. The four is the introduction of strengthening county safety production supervisment tblishment of enterprise production safety hidden With self correction self reporting system, promote the enterprises to impleilities bear safety production supervision departments strictly and effectively assumed responsibility. The three is the estaponsibh responsibility, a pair of responsibility. "Two is issued safety production administration and inspection to promote the resd management responsibilities > (Hunan Zhengban made 2013 No. 4), resolutely implement the safety production of the party witthe provisions of Hunan province safety production supervision aneople werers 6 psolute struggle and discredit the views of the party in 2012. The style of the big consolidation activities, cadres and workerinciple problems of ambiguous attitude, major issues issues of right and wrong, it cannot stand up bravely, face to face, rejor pe perfect power control mechanism on "let things drift", get free in the political norms of leading cadres, some involving maproblem of production safety as the starting point and goal of all work, to strengthen internal supervision on the way, in th listic- 4 - 山东省最大的中小学课外辅导 www.dz211.com 22xy12.(福建卷第6题) 以双曲线的右焦点为圆心，且与其渐近线相切的圆的方程是,,1916 ( ) 2222A( B( xyx，,，,1090xyx，,，,10160 2222C( D( xyx，，，,10160xyx，，，,1090 4解答:由题知圆心坐标应为(5，0)，排除C，D. 又因为点(5，0)到渐近线的距y,,x3离为4，验证可知A项正确. 答案为A . 【说明】 本题考查双曲线的基本运算以及直线与圆的相关知识. he party in 2012. The style of the big consolidation activities, cadres and workers 6 people weres of te, major issues issues of right and wrong, it cannot stand up bravely, face to face, resolute struggle and discredit the viewhings drift", get free in the political norms of leading cadres, some involving major principle problems of ambiguous attitudlet tarting point and goal of all work, to strengthen internal supervision on the way, in the perfect power control mechanism on "prohibitions", to solve the people most concerned, the most direct, the most realistic problem of production safety as the st f "tenety himittee, county government On strengthening style construction requirements and style construction safety supervision system ot, the implementation does not survive the problem. A few leading cadres not strictly in accordance with the county Party comstric on. Over the years, the global leadership team members do not have any illegal and other bad records, but there are still not. Adhere to the political principles against unwholesome tendencies existence of the problem is not strict internal supervisifour)tation of safe production of "one vote veto" award and recognition system, strengthen production safety incentive mechanism (the stagnation led the lump sum, to tackle tough. To further increase the production safety index assessment, strict implemension departments strictly and effectively assumed responsibility. The three is the establishment of enterprise production saf le forem. Production safety of key towns, key enterprises and key problems, by the township government and the Department responsibe safe" principle, the implementation of safe production supervision and stagnation to cure. "The leadership responsible systust bwho is responsible for the pipe industry must pipes, pipe production and management must control safety management business m production responsibility to the grassroots. 3, strict accountability and target management. Adhere to the "who is in charge,safe "Two is issued safety production administration and inspection to promote the responsibilities bear safety production supervisafety. The four is the introduction of strengthening county safety production supervision ability construction work, promotedden With self correction self reporting system, promote the enterprises to implement the main responsibility for production . 4), resolutely implement the safety production of the party with responsibility, a pair of responsibility. the provisions of Hunan province safety production supervision and management responsibilities > (Hunan Zhengban made 2013 No-- 5 5 -- - 5 - 提分热线: 提分太快 请系好安全带～ 中高考热门资料库(免费下载):