发布时间 : 星期六 文章2011学年衢州二中高三文科寒假作业答案更新完毕开始阅读
是DM与平面ABEF所成的角。在RTDHM中，
DH?22，DM?2?sin?DMH?DH1?DM?2，??DMH?6
所以DM与平面ABEF所成的角为
?6。 21．（Ⅰ）解：设直线PC的方程为：y?kx?3，
由
|k?3|1得k2?1?k?
43，所以PC的方程为y?43x?3. （Ⅱ）
22．解（Ⅰ）f?(x)?x?3x?(a?6)≥0对x?[3,??)恒成立
∴a≥6?(x?33x) 又g(x)?x?x在x?[3,??)为单调递增函数
∴x?3x?3?1?4 ∴a≥2
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1（Ⅱ）设t?ex，R(t)?|t?a|?a2 t?[1,3]
212??t?a?a1≤t?a??2当2≤a≤3时，R(t)??
1?t?a?a2a≤t?3??21∴R(t)最小值为R(a)?a2
21当a?3时，R(t)??t?a?a2，
21∴R(t)最小值为R(3)?a?3?a2
21综上，当2≤a≤3时，g(x)最小值为a2，
21当a?3时，g(x)最小值为a?3?a2
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练习四
一、选择题 1 B 2 D 3 A 4 C 5 C 6 C 7 D 8 C 9 B 10 A 二、填空题
33? 13．20 14． 15．相离
5616．略 17．[2,??)
11．64 0.4 12．三、解答题 18．（Ⅰ）??2 （Ⅱ）a?13 19．（Ⅰ）an?3n
（Ⅱ）bn?2n?1?Tn?n2?2n
20．解析（Ⅰ）：∵CD∥AB，AB?面PAB，CD?面PAB，
∴CD∥面PAB
（Ⅱ）∵CD∥AB，CD⊥PD ∴CD⊥面PAD，
∴CD⊥PA，又EF∥PA ∴EF与CD所成角为90° （Ⅲ）当Q是AD中点时，有QF⊥面PBC.
取PC中点K，连DK，FK，则DK⊥面PBC. 又FK∥AD，FK=AD， ∴QF∥DK∴QF⊥面PBC
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21．解析（Ⅰ）设直线AB方程为:x?ky?m,抛物线方程为:y2?2px(p?0),
?y2?2px由 ? 得, y2?2pky?2pm?0,
?x?ky?m?y1?y2?2pk设A(x1,y1),B(x2,y2),则有?,
yy??2pm?12由题意, |?2pm|?2m?2p?2,
故所求抛物线方程为:y2?2x; （Ⅱ）S?AOB?（
11|OM||y1?y2|?m4k2?8m?m2m 22Ⅲ
）
cos?AOB?OA?OB|OA|?|OB|?x1x2?y1y22(x12?2x1)(x2?2x2)?1??,
22m4k2?8m3(m2?2m)?0?m?22 ??2?0?m?23?3m?20m?12?4k?013222．解（Ⅰ）当m?2时，f?x??x?2x?3x,
32则f??x??x?4x?3，故f??0??3，
函数y?f(x)的图象在点(0,0)处的切线方程为y?3x。
33222（Ⅱ）f??x??x?2mx?m?(x?m)?m?m，
22332当m?m?0，又m?0，即0?m?时，f??x??0， 22则函数y?f(x)在(??,??)上是增函数； 332当m?m?0，又m?0，即m?时， 223322由f??x??0，得x?m?m?m或x?m?m?m，
223322由f??x??0，得m?m?m?x?m?m?m，
223322故函数f(x)在区间(??,m?m?m)和(m?m?m,??)上是增函数，
223322在区间(m?m?m,m?m?m)上是减函数，
2232（Ⅲ）因为函数f(x)既有极大值，又有极小值，则f??x??x?2mx?m?0有两个不
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同的根，则有??4m2?6m?0, 又m?0,?m?令g(x)?f(x)?mx?(m?3m)x?23 23132x?2mx2?3m2x
23g?(x)?x2?4mx?3m2?0?x?m,或x?3m，
?g?(x)?0?x?m或x?3m,g?(x)?0?m?x?3m
?g(x)在?0,m?,?3m,4m?上为增函数,在?m,3m?上为减函数,
44?g(m)?m3,g(3m)?0为g(x)的极值,又g(0)?0,g(4m)?m3，
334432?m?2 ?g(x)最大值为m3，?m3?3333m的取值范围为?m?2。
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英语学科
练习一
I. 1-5 BDCDB 6-10 BDBCC
II. 1—5 CBDAD 6—10 DACBB 11—15 DCABC 16—20 ADCAB III.
When I first learned to write in English，I run into many difficulties．The main problem ran
was in that I always thought in Chinese but tried to translate everything into Chinese．My and
teacher advised me to keep diaries. I followed her advices．Happily it worked．Soon I began advice
to enjoy talk to myself on paper as I was learning to express me in simple English．One day talking myself
I wrote a short story and showed/\\to my teacher．She liked it very much that she read it it so
to the class.Everyone said the story was the good one．I was great encouraged by their · a greatly
练习二
I. 1-5ACDAB 6-10 DABBB II. 1—5 ABCDD 6—10 BBABA 11—15. D DCCA 16—20 AAAAA III.
I often quarrel about my mother over whether I can watch TV after
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