2008年高考全国二卷理科数学题及其答案

  • 格式:doc
  • 大小:1.37 MB
  • 文档页数:11

2008年普通高等学校招生全国统一考试(全国卷2数学)理科数学(必修+选修Ⅱ)第Ⅰ卷一、选择题1.设集合{|32}M m m =∈-<<Z ,{|13}N n n M N =∈-=Z I 则,≤≤( ) A .{}01,B .{}101-,,C .{}012,,D .{}1012-,,,2.设a b ∈R ,且0b ≠,若复数3()a bi +是实数,则( ) A .223b a = B .223a b =C .229b a =D .229a b =3.函数1()f x x x=-的图像关于( ) A .y 轴对称 B . 直线x y -=对称 C . 坐标原点对称 D . 直线x y =对称4.若13(1)ln 2ln ln x e a x b x c x -∈===,,,,,则( ) A .a <b <cB .c <a <bC . b <a <cD . b <c <a5.设变量x y ,满足约束条件:222y x x y x ⎧⎪+⎨⎪-⎩,,.≥≤≥,则y x z 3-=的最小值( )A .2-B .4-C .6-D .8-6.从20名男同学,10名女同学中任选3名参加体能测试,则选到的3名同学中既有男同学又有女同学的概率为( ) A .929B .1029C .1929D .20297.64(1(1的展开式中x 的系数是( )A .4-B .3-C .3D .48.若动直线x a =与函数()sin f x x =和()cos g x x =的图像分别交于M N ,两点,则MN 的最大值为( ) A .1BCD .29.设1a >,则双曲线22221(1)x y a a -=+的离心率e 的取值范围是( ) A. B.C .(25),D.(210.已知正四棱锥S ABCD -的侧棱长与底面边长都相等,E 是SB 的中点,则AE SD ,所成的角的余弦值为( )A .13B C D .2311.等腰三角形两腰所在直线的方程分别为20x y +-=与740x y --=,原点在等腰三角形的底边上,则底边所在直线的斜率为( ) A .3B .2C .13-D .12-12.已知球的半径为2,相互垂直的两个平面分别截球面得两个圆.若两圆的公共弦长为2,则两圆的圆心距等于( ) A .1B .2C .3D .2第Ⅱ卷二、填空题:本大题共4小题,每小题5分,共20分.把答案填在题中横线上. 13.设向量(12)(23)==,,,a b ,若向量λ+a b 与向量(47)=--,c 共线,则=λ . 14.设曲线axy e =在点(01),处的切线与直线210x y ++=垂直,则a = .15.已知F 是抛物线24C y x =:的焦点,过F 且斜率为1的直线交C 于A B ,两点.设FA FB >,则FA 与FB 的比值等于 .16.平面内的一个四边形为平行四边形的充要条件有多个,如两组对边分别平行,类似地,写出空间中的一个四棱柱为平行六面体的两个充要条件:充要条件① ; 充要条件② . (写出你认为正确的两个充要条件)三、解答题:本大题共6小题,共70分.解答应写出文字说明,证明过程或演算步骤. 17.(本小题满分10分) 在ABC △中,5cos 13B =-,4cos 5C =. (Ⅰ)求sin A 的值;(Ⅱ)设ABC △的面积332ABC S =△,求BC 的长. 18.(本小题满分12分)购买某种保险,每个投保人每年度向保险公司交纳保费a 元,若投保人在购买保险的一年度内出险,则可以获得10 000元的赔偿金.假定在一年度内有10 000人购买了这种保险,且各投保人是否出险相互独立.已知保险公司在一年度内至少支付赔偿金10 000元的概率为41010.999-.(Ⅰ)求一投保人在一年度内出险的概率p ;(Ⅱ)设保险公司开办该项险种业务除赔偿金外的成本为50 000元,为保证盈利的期望不小于0,求每位投保人应交纳的最低保费(单位:元).19.(本小题满分12分)如图,正四棱柱1111ABCD A B C D -中,124AA AB ==,点E 在1CC 上且EC E C 31=.(Ⅰ)证明:1AC ⊥平面BED ; (Ⅱ)求二面角1A DE B --的大小. 20.(本小题满分12分)设数列{}n a 的前n 项和为n S .已知1a a =,13n n n a S +=+,*n ∈N .(Ⅰ)设3nn n b S =-,求数列{}n b 的通项公式;(Ⅱ)若1n n a a +≥,*n ∈N ,求a 的取值范围.21.(本小题满分12分)设椭圆中心在坐标原点,(20)(01)A B ,,,是它的两个顶点,直线)0(>=k kx y 与AB 相交于点D ,与椭圆相交于E 、F 两点.(Ⅰ)若6ED DF =u u u r u u u r,求k 的值;(Ⅱ)求四边形AEBF 面积的最大值. 22.(本小题满分12分) 设函数sin ()2cos xf x x=+.(Ⅰ)求()f x 的单调区间;(Ⅱ)如果对任何0x ≥,都有()f x ax ≤,求a 的取值范围.AB CD EA 1B 1C 1D 12008年参考答案和评分参考一、选择题1.B 2.A 3.C 4.C 5.D 6.D 7.B 8.B 9.B 10.C 11.A 12.C部分题解析:2. 设a b ∈R ,且0b ≠,若复数3()a bi +是实数,则( )A .223b a =B .223a b =C .229b a =D .229a b =,解:33223()33()()a bi a a bi a bi bi +=+++gg (←考查和的立方公式,或二项式定理) 3223(3)(3)a a b a b b i =-+-gg (←考查虚数单位i 的运算性质) R ∈ (←题设条件)∵a b ∈R ,且0b ≠∴ 2330a b b -=g(←考查复数与实数的概念) ∴ 223b a =. 故选A.6. 从20名男同学,10名女同学中任选3名参加体能测试,则选到的3名同学中既有男同学又有女同学的概率为( ) A .929B .1029C .1929D .2029思路1:设事件A :“选到的3名同学中既有男同学又有女同学”,其概率为:211220102010330()C C C C P A C += (←考查组合应用及概率计算公式) 201910910202121302928321⨯⨯⨯+⨯⨯⨯=⨯⨯⨯⨯ (←考查组合数公式) 10191010109102914⨯⨯+⨯⨯=⨯⨯ (←考查运算技能)2029=故选D.思路2:设事件A :“选到的3名同学中既有男同学又有女同学”,事件A 的对立事件为A :“选到的3名同学中要么全男同学要么全女同学”其概率为:()1()P A P A =- (←考查对立事件概率计算公式)3320103301C C C +=- (←考查组合应用及概率计算公式)2019810983213211302928321⨯⨯⨯⨯+⨯⨯⨯⨯=-⨯⨯⨯⨯(←考查组合数公式) 2019181098302928⨯⨯+⨯⨯=⨯⨯ (←考查运算技能)2029=故选D.12.已知球的半径为2,相互垂直的两个平面分别截球面得两个圆.若两圆的公共弦长为2,则两圆的圆心距等于( ) A .1B .2C .3D .2分析:如果把公共弦长为2的相互垂直的两个截球面圆,想成一般情况,问题解决起来就比较麻烦,许多考生就是因为这样思考的,所以浪费了很多时间才得道答案;但是,如果把公共弦长为2的相互垂直的两个截球面圆,想成其中一个恰好是大圆,那么两圆的圆心距就是球心到另一个小圆的距离3,问题解决起来就很容易了. 二、填空题13.2 14.2 5.3+16.两组相对侧面分别平行;一组相对侧面平行且全等;对角线交于一点;底面是平行四边形. 注:上面给出了四个充要条件.如果考生写出其他正确答案,同样给分. 三、解答题 17.解:(Ⅰ)由5cos 13B =-,得12sin 13B =, 由4cos 5C =,得3sin 5C =.所以33sin sin()sin cos cos sin 65A B C B C B C =+=+=. ···································· 5分 (Ⅱ)由332ABC S =△得133sin 22AB AC A ⨯⨯⨯=, 由(Ⅰ)知33sin 65A =,故65AB AC ⨯=, ························································································ 8分又sin 20sin 13AB B AC AB C ⨯==, 故2206513AB =,132AB =. 所以sin 11sin 2AB A BC C ⨯==. ········································································· 10分18.解:各投保人是否出险互相独立,且出险的概率都是p ,记投保的10 000人中出险的人数为ξ,则4~(10)B p ξ,.(Ⅰ)记A 表示事件:保险公司为该险种至少支付10 000元赔偿金,则A 发生当且仅当0ξ=, ·················································································································· 2分()1()P A P A =-1(0)P ξ=-=4101(1)p =--,又410()10.999P A =-,故0.001p =. ······························································································ 5分 (Ⅱ)该险种总收入为10000a 元,支出是赔偿金总额与成本的和. 支出 1000050000ξ+,盈利 10000(1000050000)a ηξ=-+,盈利的期望为 100001000050000E a E ηξ=--, ·········································· 9分由43~(1010)B ξ-,知,31000010E ξ-=⨯, 4441010510E a E ηξ=--⨯4443410101010510a -=-⨯⨯-⨯. 0E η≥4441010105100a ⇔-⨯-⨯≥1050a ⇔--≥ 15a ⇔≥(元).故每位投保人应交纳的最低保费为15元. ························································· 12分19.解法一:依题设知2AB =,1CE =.(Ⅰ)连结AC 交BD 于点F ,则BD AC ⊥. 由三垂线定理知,1BD A C ⊥. ········································································ 3分 在平面1A CA 内,连结EF 交1A C 于点G ,由于1AA ACFC CE== AB CD EA 1B 1C 1D 1FH G故1Rt Rt A AC FCE △∽△,1AA C CFE ∠=∠,CFE ∠与1FCA ∠互余.于是1A C EF ⊥.1A C 与平面BED 内两条相交直线BD EF ,都垂直,所以1A C ⊥平面BED . ················································································· 6分 (Ⅱ)作GH DE ⊥,垂足为H ,连结1A H .由三垂线定理知1A H DE ⊥,故1A HG ∠是二面角1A DE B --的平面角. ······················································· 8分EF =CE CF CG EF ⨯==EG == 13EG EF =,13EF FD GH DE ⨯=⨯=.又1AC ==11A G A C CG =-=.11tan AG A HG HG∠== 所以二面角1A DE B --的大小为arctan . ·················································· 12分 解法二:以D 为坐标原点,射线DA 为x 轴的正半轴, 建立如图所示直角坐标系D xyz -.依题设,1(220)(020)(021)(204)B C E A ,,,,,,,,,,,.(021)(220)DE DB ==u u u r u u u r,,,,,,11(224)(204)AC DA =--=u u u r u u u u r,,,,,. ···································································· 3分 (Ⅰ)因为10AC DB =u u u r u u u r g ,10AC DE =u u u r u u u rg, 故1A C BD ⊥,1A C DE ⊥. 又DB DE D =I ,所以1AC ⊥平面DBE .·················································································· 6分 (Ⅱ)设向量()x y z =r,,n 是平面1DA E 的法向量,则DE ⊥u u ur r n ,1DA ⊥u u u u r r n .故20y z +=,240x z +=.令1y =,则2z =-,4x =,(412)=-r,,n . ····················································· 9分 1AC u u u rr ,n 等于二面角1A DE B --的平面角,111cos A C A C A C==u u u r r u u u r r g u u u r r ,n n n . 所以二面角1A DE B --的大小为. ················································· 12分 20.解:(Ⅰ)依题意,113nn n n n S S a S ++-==+,即123n n n S S +=+,由此得1132(3)n n n n S S ++-=-. ······································································· 4分因此,所求通项公式为13(3)2n n n n b S a -=-=-,*n ∈N .① ····························································· 6分(Ⅱ)由①知13(3)2n n n S a -=+-,*n ∈N ,于是,当2n ≥时,1n n n a S S -=-1123(3)23(3)2n n n n a a ---=+-⨯---⨯ 1223(3)2n n a --=⨯+-, 12143(3)2n n n n a a a --+-=⨯+-22321232n n a --⎡⎤⎛⎫=+-⎢⎥ ⎪⎝⎭⎢⎥⎣⎦g ,当2n ≥时,21312302n n n a a a -+⎛⎫⇔+- ⎪⎝⎭g ≥≥9a ⇔-≥.又2113a a a =+>.综上,所求的a 的取值范围是[)9-+∞,. ························································· 12分 21.(Ⅰ)解:依题设得椭圆的方程为2214x y +=, 直线AB EF ,的方程分别为22x y +=,(0)y kx k =>. ····································· 2分 如图,设001122()()()D x kx E x kx F x kx ,,,,,,其中12x x <, 且12x x ,满足方程22(14)4k x +=,故21x x =-=.①由6ED DF =u u u r u u u r 知01206()x x x x -=-,得021215(6)77x x x x =+==;由D 在AB 上知0022x kx +=,得0212x k=+. 所以212k =+,化简得2242560k k -+=,解得23k =或38k =. ····················································································· 6分 (Ⅱ)解法一:根据点到直线的距离公式和①式知,点E F ,到AB 的距离分别为1h ==2h ==. ······················································ 9分又AB ==,所以四边形AEBF 的面积为121()2S AB h h =+ 12===≤当21k =,即当12k =时,上式取等号.所以S 的最大值为 ························· 12分 解法二:由题设,1BO =,2AO =.设11y kx =,22y kx =,由①得20x >,210y y =->, 故四边形AEBF 的面积为BEF AEF S S S =+△△222x y =+ ··································································································· 9分===当222x y =时,上式取等号.所以S 的最大值为. ······································· 12分 22.解: (Ⅰ)22(2cos )cos sin (sin )2cos 1()(2cos )(2cos )x x x x x f x x x +--+'==++.····························· 2分当2π2π2π2π33k x k -<<+(k ∈Z )时,1cos 2x >-,即()0f x '>; 当2π4π2π2π33k x k +<<+(k ∈Z )时,1cos 2x <-,即()0f x '<.因此()f x 在每一个区间2π2π2π2π33k k ⎛⎫-+ ⎪⎝⎭,(k ∈Z )是增函数, ()f x 在每一个区间2π4π2π2π33k k ⎛⎫++ ⎪⎝⎭,(k ∈Z )是减函数. ···························· 6分 (Ⅱ)令()()g x ax f x =-,则第11页(共11页) 22cos 1()(2cos )x g x a x +'=-+ 2232cos (2cos )a x x =-+++ 211132cos 33a x ⎛⎫=-+- ⎪+⎝⎭. 故当13a ≥时,()0g x '≥. 又(0)0g =,所以当0x ≥时,()(0)0g x g =≥,即()f x ax ≤. ······················· 9分 当103a <<时,令()sin 3h x x ax =-,则()cos 3h x x a '=-. 故当[)0arccos3x a ∈,时,()0h x '>.因此()h x 在[)0arccos3a ,上单调增加.故当(0arccos3)x a ∈,时,()(0)0h x h >=,即sin 3x ax >.于是,当(0arccos3)x a ∈,时,sin sin ()2cos 3x x f x ax x =>>+. 当0a ≤时,有π1π0222f a ⎛⎫=> ⎪⎝⎭g ≥. 因此,a 的取值范围是13⎡⎫+∞⎪⎢⎣⎭,. ··································································· 12分。