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高一数学答案第1页(共6页)PQCDAB2020~2021学年度第二学期期末考试高一数学参考答案及评分标准2021.7一、选择题:本题共8小题,每小题5分,共40分.在每小题给出的四个选项中,只有一项是符合题目要求的.1~4
:DBCC5~8:AABC二、选择题:本题共4小题,每小题5分,共20分.在每小题给出的选项中,有多项符合题目要求.全部选对的得5分,部分选对的得2分,有选错的得0分.9.BCD10.AD11.ABD12.BC三、填空题:本题共4小题,每小题5分,共20分.13
.1i14.18π15.1(2,1)216.262四、解答题:本题共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.(本题满分10分)解:(1)因为P、Q分别为BC、CD的中点,所以12APABBPA
BAD;12BQCQCBABAD.······················································2分于是ACAPBQ11()()22ABADABAD
11()()22ABAD.············································3分又ACABAD,由平面向量基本定理,得11,211.2·
····················4分解得65,25.·····································································5分(2)由(1)可知1
2APABAD,12BQABAD,高一数学答案第2页(共6页)PQCDAB所以22211121||()22422APABADABADABAD;········6分222111||()21242B
QABADABABADAD;················7分11()()22APBQABADABAD22131242ABABADAD221313221cos6012424
.·····························8分所以3214cos,14||||2112APBQAPBQAPBQ.··························10分
18.(本题满分12分)解:(1)因为PC平面ABC,AC平面ABC,所以ACPC.·······························2分因为C是以AB为直径的圆O上的点,所以ACBC.·······························4分
又PCBCC,所以AC平面PBC...........................................................5分因为E,F分别是PA,PC的中点,所以EFAC..........
..........................6分所以EF平面PBC.....................................................................
......................7分又EF平面BEF,故平面BEF平面PBC.................................................8分(2)EFl..................................
..................................................................................9分证明如下:由(1),EFAC.又AC平面ABC,EF平面ABC,所以EF平面A
BC..........................................................................................10分又EF平面BEF,平面BEF平面AB
Cl,所以EFl.........................................................................................................12分FECAPB高一数学答案第
3页(共6页)19.(本题满分12分)解:(1)由题意,得1(1)(1),61(1)(1).2pqpqpq·····································
·············2分解得13pq,76pq.所以,pq是方程271063xx的两个实根.又pq,解得23p,12q.·············································
·········4分(2)解法一:设1A,2A分别表示甲两轮猜对1个,2个谜语的事件,1B,2B分别表示乙两轮猜对1个,2个谜语的事件,则121124()33339PA,2224()339PA,11111
1()22222PB,2111()224PB.·································8分设M表示“星队”在前两轮活动中猜对3个谜语的事件,由题意,1221()()PMPABAB········
············································9分1221()()PABPAB········································
·······10分1221()()()()PAPBPAPB······································11分4141194923.·············································12分解法二:设1A,2
A分别表示第一轮两人猜对1个,2个谜语的事件,1B,2B分别表示第二轮两人猜对1个,2个谜语的事件,则121111()32322PA,2211()323PA,121111()32322PB
,2211()323PB.································8分设M表示“星队”在前两轮活动中猜对3个谜语的事件,由题意,1221()()PMPABAB···················
·································9分1221()()PABPAB···············································10分1221
()()()()PAPBPAPB······································11分1111123323.·············································12分高一数学答案第4页(共6页)2
0.(本题满分12分)解:(1)由cos3sinbAbAca及正弦定理,得sincos3sinsinsinsinBABACA①·········································2分因为π()
CAB,所以sinsin()sincoscossinCABABAB②·······························4分将②代入①得sincos3sinsinsincoscossinsinBABAABABA,即3sinsinsincossinB
AABA.··············································5分又sin0A,所以有3sincos1BB,即223sincos2cos222BBB.因
为π(0,)22B,所以cos02B,于是有3sincos22BB,即3tan23B.········································7分又π(0,)22B,所以π26B,即π3
B.············································8分(2)由△ABC的面积为3,得1πsin323ac,即4ac.·····················9分由余弦定理
,得222π2cos3bacac,即22π()2(1cos)3acacb.·····················································10分将4ac,2b代入上式,得21()24(1)42ac.解得4ac.···
·······································································11分所以a,c是方程2440xx的两个实根,显然2ac.·············12分高一数学答案第5页(共6页)EDACBB'C'A'ED
ACBB'C'A'21.(本题满分12分)解:(1)取线段AC的中点E,连接BE,CB,CE,则平面BEC平面ABD.BE,CB,CE即为应画的线.··············································
·······2分证明如下:因为D为AC的中点,E为AC的中点,所以AEDC,且AEDC,所以四边形AECD为平行四边形,所以DACE.·································3分又DA平面ABD
,CE平面ABD,所以CE平面ABD.··································································4分连接DE,则DEAA,
DEAA.又BBAA,BBAA,所以DEBB,DEBB,所以四边形DEBB是平行四边形,所以BEBD.···········································································5
分又BD平面ABD,BE平面ABD,所以BE平面ABD.··································································6分又CEBEE
,CE平面BEC,BE平面BEC,故平面BEC平面ABD.·····························································8分(2)设棱柱ABCABC
的底面积为S,高为h,则30SVh三棱柱.111()5326BCAABECDVVShSh三棱锥三棱锥.······························10分所以三棱柱夹在平面BEC与平面ABD之间部分的体积30
5520ABCABCAABBCDCEVVVV三棱柱三棱锥三棱锥.···············12分高一数学答案第6页(共6页)22.(本题满分12分)解:(1)因为频率分布直方图
中,所有小矩形的面积之和为1,所以40.0640.0840.0440.0440.02441aa,即0.9681a.······························································
···········1分故0.005a.·············································································3分该市居民月均用水量的平均值3.
2(40.06)7.2(40.08)11.2(40.04)15.2(40.04)x19.2(40.02)23.2(40.005)27.2(40.005)···················4分9.84.··················
·································································6分(2)由频率分布直方图知月均用水量在13.2t以下的居民用户所占的比例为40.064
0.0840.040.72.·····································7分月均用水量在17.2t以下的居民用户所占的比例为0.7240.040.88.······················
·······························8分因此,第80百分位数一定位于[13.2,17.2)内,0.80.7213.2415.20.880.72.················
····························10分因此,要使80%的居民用户生活用水费用支出不受影响,一户居民月均用水量的标准A为15.2t.······················································
····················12分