P(2a?c,4c(2a?c)),在Rt?FF?P中,FF??2c,PF??2a,?FPF??90?,所以PF?2b,又在直角三角形PFM中,由勾股定理得(2a)2?(4c(2a?c)2?(2b)2即c2?ac?a2?0,所以e2?e?1?0,解之得e?1?51?5或e?(舍去). 9. 1.22得
2an?1?an?1?qan【解析】由
bnaa?n?1?n?1?qbn?1anan,,所以
222?(a1?nd)?(a1?nd?2d)?q(a1?nd?d)对n?N恒成立,从而d?qd.若d?0,则
a12?qa12,得q?1;若q?1,则d?0,综上d?q?1
10. 605 . 【解析】由f(x)?f(x?5)?16,可知f(x?5)?f(x)?16,则f(x?5)?f(x?5)?0,所以f(x)是以10为周期的周期函数. 在一
O 个周期(?1,9]上,函数f(x)?x?2在x?(?1,4]区间内有3个零点,在x?(4,9]区间内无零点,故f(x)在一个周期上仅有3个零点,而区间(?1,2009]中共包含201个周期.又函数在x??2009,2016?的图像与
A M (图1)
2xC B x???1,4?的图像相同,所以在?2009,2016?存在3个零点,而x???1,0?时存在一个
零点,故f(x)在[0,2016]上的零点个数为3?201?3?1?605.
11. 72. 【解析】法1:连结CO并延长交AB于点M(如图1),
???????????????????????? 则AC?BC?AO?OC?BO?OC
????????????????????????????????2 ?AO?BO?OC?BO?OC?AO?OC ????????????????????2 ?OC?BO?OC?AO?OC
?OC??BO?AO?OC??2OC, 因为OC?2OM?AB?6,所以AC?BC?72.
法2: 以AB的中点M为坐标原点,AB为x轴建立平面直角坐标系(如图2), 则A??3,0?,B?3,0?,
????????????????????????????2
y 设C(x,y),则易得Ox,,
?33?2y C ???????? 因为OA?OB,所以AO?BO?0,
y 从而x?3?x?3?333???????0,
A O M (图2)
化简得,x2?y2?81,
???????? 所以AC?BC?(x?3)(x?3)?y2?x2?y2?9?72. B x 12.
6.【解析】法一: 借助等量关系求变量,容易想到利用基本不等式,这也3?x?y?z?0?z??(x?y)x2?y2x?y是解决此类问题的常用方法.由?222得?由?22222x?y?z?11?z?x?y??(x?y)2z2622得x?y?,所以1?z?,解得z2?,故z的最大值是. 223322思路二: 从方程角度,该题是解的存在性问题,据此可得
代入x2?y2?z2?1得x2?(x?z)2?z2?1?0,化简得2x2?2zx?2z2?1?0,y??(x?z),
因为方程有根,所以??4z2?8(2z2?1)?0,得z2?,故z的最大值是236. 3 55?.【解析】由题意可知满足PA?2AB的点P应在以C1为圆心,半径为25的圆13. ?5 ,上及其内部(且在圆C1的外部),记该圆为C3,若圆C2上存在满足条件的点P,则圆C2与圆C3有公共点,所以
|r?25|?(17?1)2?(30?6)2?r?25,即|r?25|?30?r?25,解得5?r?55.
14.1?2?m?0. 【解析】法一:(分段函数,分类讨论)f(x)是奇函数,考查f(x)大致图象. 1o当m?0时,由于y?f(x?m)图象可以看成由y?f(x)向左平移m个单位得到,此时图象在y?f(x)上方,不合题意,舍去; 2o当m?0时,结
合图象,根据对称性及图象平移,只要f(?1?m)?f(?1)即可, 所以
(?1?m)?1?m?(?1?m)??(?1)?1?m?(?1)?,即?m(m?1)2?m?1??m?1即?m(m?1)2??2m
因为m?0,所以(m?1)2?2,解得1?2?m?1?2,所以m的取值范围为1?2?m?0.
图(1)
法二:(特殊化思想、数形结合)由题意知,当x?0时,f(x)?f(x?m)成立,所以f(0)?f(m)
所以m(1?mm)?0,解得?1?m?0,因为f(x)为奇函数,因此该函数图象关于原点对称,如图(1),而y?f(x?m)表示将y?f(x)图像向右平移?m个单位,由于?1?m?0,因此只可能得到如图所示的图象,并与f(x)图象的左交点A必在y轴左侧. 由题意??1,1??M,f(x)?f(x?m)恒成立,结合图象即??1,1??(x1,x2),根据区间对称性及图象特征,只要x1??1即可.用\x?0\的部分,由f(x?m)?f(x)得
1?m2(x?m)?1?m(x?m)??x(1?mx),整理得2mx?m?1?0,解得xA?,
2m21?m2??1,得1?2?m?1?2,结合?1?m?0,故所求m取值范围为由2m1?2?m?0.
二、解答题
15 .(1)因为MN∥平面PAB,MN?平面ABC,
平面PAB?平面ABC?AB,所以MN∥AB. ·······················3分
因为MN?平面PMN,AB?平面PMN,
所以AB∥平面PMN. ································································6分 (2)因为M为BC的中点,MN∥AB,
所以N为AC的中点. ································································8分 因为BC?4,AC?2,所以MC?2,NC?1, 由于MN?3,所以MN2?NC2?MC2,
所以MN?AC. ··································································10分 因为PA?PC,AN?CN,所以PN?AC, 又MN,PN?平面PMN,MN?PN?N,
所以AC?平面PMN. ·······························································12分 因为AC?平面ABC,
所以平面ABC?平面PMN. ····························································14分
3,即4113, ···········································2分 S?absinC?a?3asinC?2241所以 sinC?2 ,由余弦定理,得c2?a2?3a2?2a?3acosC,
2a16. 法1:因为?ABC的面积为
又已知c?1, ···········································4分
1(4a2?1)2?1,从而 故cosC?.,再由sinC?cosC?1,得 4?424a12a23a224a2?1a?1. ···········································6分 (2)因为cosC?3,所以由余弦定理c2?a2?b2?2abcosC,得c?2a,又b?3a,, 3··········································8分 从而b2?a2?c2故B?900. ·而由b?3a及正弦定理可得sinA?因此cos(B?A)?cos(900?A)?sinA?3, ··········································10分 33. ···········································14分 317.(1)因为?AOE??,?AOE??BOF且OA?OB?1,
所以AD?1?cos??sin?,BC?1?cos??sin? ,AB?2cos?.·······················4分 所以SABCD=(AD?BC)?AB?······················6分 ?2(1?sin?)cos?,其中0???. ·
22f'(?)?2(cos2??sin??sin2?) (2)记f(?)?2(1?sin?)cos?, ?2(1?sin2??sin??sin2?)??2(2sin2??sin??1) ??2(2sin??1)(sin??1)0???当0???时,f'(?)?0,当 所以当且仅当??即???6??. ·······················10分 2???······················12分 ???时,f'(?)?0, ·
62?33?时f(?)max?f. ?626??33?时,Smax?.
26?6?当θ取时,梯形铁片ABCD的面积S最大,最大值为33.·············14分 2
a218.(1)因为F是AT的中点,所以?a??2c,即(a?2c)(a?c)?0,又a、c?0,
c所以a?2c,所以e?c1?;······················2分 a2(2)①解法一:过M,N作直线的垂线,垂足分别为M1,N1,依题意,
NFMF·········4分 ??e,·
NN1MM1又NF?2MF,故NN1?2MM1,故M是NT的中点,∴S?MNF1······················6?,·
S?TNF2分
又F是AT中点,∴S?ANF?S?TNF,∴S11······················8分 ?;·
S22x2y2解法二:∵a?2c,∴b?3c,椭圆方程为2?2?1,F(c,0),T(4c,0),
4c3c32x2y222设M(x1,y1),N(x2,y2),点M在椭圆2?2?1上,即有y1?3c?x1,
44c3c∴
3MF?(x1?c)2?y12?(x1?c)2?3c2?x124?1211x1?2cx1?4c2?|x1?2c|?2c?x1 422同理NF?2c?1x2,··········4分 2S?MNF1·····················6?,·
S?TNF2又NF?2MF,故2x1?x2?4c得M是N,T的中点,∴分
又F是AT中点,∴S?ANF?S?TNF,∴S11·····················8分 ?;·
S22x2y2②解法一:设F(c,0),则椭圆方程为2?2?1,
4c3c