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2018海淀区高三理科数学二模试题及答案

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B

C D B A C C A 第二部分(非选择题共110分)

二、填空题共6小题,每小题5分,共30分. (9)1(10)10

(11)1;23(12)

7 3(13)答案不唯一,a?0或a?4的任意实数(14)

25 5

三、解答题共6小题,共80分.解答应写出文字说明,演算步骤或证明过程. (15)(本小题13分) 解:(Ⅰ)A?2,??2,????······································································· 7分 . 3?(Ⅱ)由(Ⅰ)得,f(x)?2sin(2x?).

3?1········································· 8分 因为f(?)?1,所以sin(2??)?. ·

325?2???································· 9分 ,),所以2???(,?). ·因为??(12332?5·································································· 11分 所以2????, ·

367········································································ 12分 所以2???, ·

6所以cos2??cos???763····················································· 13分 . 2

16. (本小题共13分)

解:(Ⅰ)这10名学生的考核成绩(单位:分)分别为:

93,89.5,89,88,90,88.5,91.5,91,90.5,91.

· 1分 其中大于等于90分的有1号、5号、7号、8号、9号、10号,共6人. ·

所以样本中学生考核成绩大于等于90分的频率为:

6?0.6, ································································ 3分 10从该校高二年级随机选取一名学生,估计这名学生考核成绩大于等于90分的概率为0.6. ································································································································ 4分

(Ⅱ)设事件A:从上述考核成绩大于等于90分的学生中再随机抽取两名同学,这两

····················································· 5分 名同学两轮测试成绩均大于等于90分. ·

由(Ⅰ)知,上述考核成绩大于等于90分的学生共6人,其中两轮测试成绩均大于等

········································· 6分 于90分的学生有1号,8号,10号,共3人. ·

C3231?. ························································· 9分 所以,P(A)?2?C615522·································································· 13分 (Ⅲ)x1?x2,s1?s2. ·

17.(本小题共14分) 解:(Ⅰ)因为AB1⊥平面ABC,AC?平面ABC,

··············································································· 1分 所以AB1?AC. ·

因为AC1?AC,AB1AC1?A,AB1,AC1?平面AB1C1,

····························································· 3分 所以AC?平面AB1C1. ·因为B1C1?平面AB1C1,

······································································ 4分 所以AC?B1C1. ·

(Ⅱ)法一:取A1B1的中点M,连接MA、ME. 因为E、M分别是B1C1、A1B1的中点, 所以ME∥A1C1,且ME?1A1C1. ························································ 5分 2C A1C1,且AD?在三棱柱ABC?A1B1C1中,AD1AC11, 21 E B 1 A 1 M 所以ME∥AD,且ME=AD,

············· 6分 所以四边形ADEM是平行四边形, ·

······································ 7分 所以DE∥AM. ·

又AM?平面AA1B1B,DE?平面AA1B1B, ························· 9分 所以DE//平面AA1BB. ·

注:与此法类似,还可取AB的中点M,连接MD、MB1. 法二:取AB的中点M,连接MD、MB1. 因为D、M分别是AC、AB的中点,

C B D A C 1 A1

B1 E 1BC. ·················· 5分 21在三棱柱ABC?A1B1C1中,B1EBC,且B1E?BC,

2C 所以MD∥B1E,且MD=B1E,

··········· 6分 所以四边形B1E DM是平行四边形, ·

····································· 7分 所以DE∥MB1. ·

又MB1?平面AA1B1B,DE?平面AA1B1B,

所以MD∥BC,且MD?························· 9分 所以DE//平面AA1BB. ·

法三:取BC的中点M,连接MD、ME. 因为D、M分别是CA、CB的中点,

D B M A ··································································· 5分 所以,DM//AB. ·

在三棱柱ABC?A1B1C1中,BC//B1C1,BC?B1C1,

C1 因为E、M分别是C1B1和CB的中点,

所以,MB//EB1,MB?EB1,

·········· 6分 所以,四边形MBB1E是平行四边形, ·

·································· 7分 所以,ME//BB1. ·又因为MEA1

E B1 MD?M,BB1AB?B,

C M D B A ME,MD?平面MDE,BB1,AB?平面AA1B1B,

············· 8分 所以,平面MDE//平面AA1B1B. ·因为,DE?平面MDE,

······················ 9分 所以,DE//平面AA1BB. ·

(Ⅲ)在三棱柱ABC?A1B1C1中,BC//B1C1, 因为AC?B1C1,所以AC?BC.

在平面ACB1内,过点C作Cz//AB1, 因为,AB1?平面ABC,

·························· 10分 所以,Cz?平面ABC. ·

建立空间直角坐标系C-xyz,如图.则

zC1EB1A1CDyABxC(0,0,0),B(2,0,0),B1(0,2,2),C1(?2,2,2),D(0,1,0),E(?1,2,2).

··························· 11分 DE?(?1,1,2),CB?(2,0,0),CB1?(0,2,2). ·设平面BB1C1C的法向量为n?(x,y,z),则

??2x?0?n?CB?0,即, ???2y?2z?0??n?CB1?0···························· 12分 得x?0,令y?1,得z??1,故n?(0,1,?1). ·设直线DE与平面BB1C1C所成的角为θ, 则sinθ=cos?DE,n??DE?n|DE|?|n|?3, 63. ·························· 14分 6所以直线DE与平面BB1C1C所成角的正弦值为

18. (本小题共14分)

x2解:(Ⅰ)在椭圆C:?y2?1中,a?2,b?1,

4···························································· 2分 所以c?a2?b2?3, ·

····················································· 3分 故椭圆C的焦距为2c?23, ·

c3·································································· 5分 . ·?a2(Ⅱ)法一:设P(x0,y0)(x0?0,y0?0),

离心率e?xx22T················· 6分 ?y0?1,故y0?1?. ·

P443222222所以|TP|?|OP|?|OT|?x0?y0?1?x0,

4OF3································· 8分 所以|TP|?x0, ·

213·········· 9分 S?OTP?|OT|?|TP|?x0. ·

2413··················· 10分 又O(0,0),F(3,0),故S?OFP?OF?y0?y0. ·

223x0······························· 11分 因此S四边形OFPT?S?OFP?S?OTP??(?y0) ·

22则

23x032???x0y0?y0??1?x0y0. 24222x0x022由?y0?1,得2?y0?1,即x0?y0?1,

4436········································· 13分 所以S四边形OFPT?, ·?1?x0y0?222x0122················· 14分 当且仅当时等号成立. ?y0?,即x0?2,y0?4222020yx(Ⅱ)法二:设P(2cos?,sin?)(0????2········································ 6分 ),

222222则|TP|?|OP|?|OT|?4cos??sin??1?3cos?,

所以|TP|?······························································· 8分 3cos?, ·

13········································ 9分 |OT|?|TP|?cos?. ·

2213··············· 10分 又O(0,0),F(3,0),故S?OFP?OF?y0?sin?. ·

223························ 11分 因此S四边形OFPT?S?OFP?S?OTP??(cos??sin?) ·

26?6········································· 13分 , ·?sin(??)?242?2···················· 14分 当且仅当??时,即x0?2,y0?时等号成立.

42S?OTP?

19.(本小题共13分)

axax················· 1分 解:(Ⅰ)法一:f'(x)?a?e?a?a?(e?1)(a?0,x?R), ·

····························································· 2分 令f'(x)?0,得x?0. ·

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