市质检数学(理科)参考解答与评分标准 第 1页 共 12页
泉州市 2020 届普通高中毕业班第一次质量检查
理科数学试题答案及评分参考
评分说明:
1.本解答给出了一种或几种解法供参考,如果考生的解法与本解答不同,可根据试题的主要考
查内容比照评分标准制定相应的评分细则.
2.对计算题,当考生的解答在某一步出现错误时,如果后继部分的解答未改变该题的内容和难
度,可视影响的程度决定后继部分的给分,但不得超过该部分正确解答应给分数的一半;如果后继部
分的解答有较严重的错误,就不再给分.
3.解答右端所注分数,表示考生正确做到这一步应得的累加分数.
4.只给整数分数.选择题和填空题不给中间分.
二、填空题:本大题共 4 小题,每小题 5 分,共 20 分.将答案填在答题卡的相应位置。
13.2 14. 4
3
15. 3( ,0)4
, 27
4 16. 2 7( ,2]7
三、解答题:共 70 分。解答应写出文字说明,证明过程或演算步骤。第 17~21 题为必考题,每个试题考
生都必须作答。第 22、23 题为选考题,考生根据要求作答。
(一)必考题:共 60 分。
17.本小题主要考查解三角形、三角恒等变换等基础知识,考查推理论证能力和运算求解能力等,考查数
形结合思想和化归与转化思想等,体现综合性与应用性,导向对发展直观想象、逻辑推理、数学运算
及数学建模等核心素养的关注.满分 12 分.
【解析】
思路探求 1:在 Rt ABC△ 中,由已知条件求出相关的边与角,由倍角关系推导求出 ADC△ 为等边三
角形,再利用余弦定理即求出 7BD 的长度.
(1)解法一:
在 Rt ABC△ 中,由 π= 6ACB∠ , 3BC 得
1AB , π= 3BAC∠ , 2AC ........................................................................................2 分
又 π2 = 3DAC ACB∠ ∠ , π= 3ADC∠ ,
所以 ADC△ 为等边三角形,所以 2AD .......................................................................4 分
在 ABD△ 中,由余弦定理得, 2 2 2 2 cosBD AB AD AB AD BAD ∠ ,
即 2 2 2 2π1 2 2 1 2 cos =73BD ,解得 7BD ..............................................6 分
思路探求 2:在 Rt ABC△ 中,由已知条件求出相关的边与角,由倍角关系推导求出 ADC△ 为等边三
角形,再由角的关系推导出 ABD△ 是直角三角形,利用勾股定理即求出 7BD 的长度.市质检数学(理科)参考解答与评分标准 第 2页 共 12页
(1)解法二:在 Rt ABC△ 中,由 π= 6ACB∠ , 3BC 得
1AB , π= 3BAC∠ , 2AC .........................................................................................2 分
又 π2 = 3DAC ACB∠ ∠ , π= 3ADC∠ ,
所以 ADC△ 为等边三角形,所以 2CD , π= 3
∠ACD ,.............................................4 分
因为 π= 6
∠ACB ,所以 π π π= + = 3 6 2
∠BCD ACB ACD ;
在 ABD△ 中,由勾股定理得 2 2 2 2 23 +2 =7( )BD CB CD ,解得 7BD .....6 分
思路探求 1:由题目已知条件 2DAC ACB∠ ∠ ,可将所要的角转化到 ACD△ 中,再将 AC 用
Rt ABC△ 中边角来表示,利用正弦定理及三角恒等变换求解即可得.
(2)解法一:
设 =ACB ∠ , AB x ,
则 2DAC ∠ , 3DC x ......................................................................7 分
在 Rt ABC△ 中, = sin sin
AB xAC ,......................................................8 分
在 ACD△ 中,根据正弦定理得,
sin sin
DC AC
DAC ADC
∠ ∠ ,
即 3 sin
πsin2 sin 3
x
x
,......................................................................10 分
π3 sin sin23 sin
xx
,
33 2sin cos2 sin
xx
..........................11 分
解得 3cos 4
,即 3cos = 4ACB∠ .......................................................................12 分
思路探求 2:由题目已知条件 2DAC ACB∠ ∠ ,可将所要的角转化到 ACD△ 中,利用正弦定理求市质检数学(理科)参考解答与评分标准 第 3页 共 12页
出 AC ,再将 AC 用 Rt ABC△ 中边角来表示,最后再由等量代换求解即可得.
(2)解法二
设 =ACB ∠ , AB x ,
则 2DAC ∠ , 3DC x .......................................................................7 分
在 ACD△ 中,根据正弦定理得,
sin sin
DC AC
DAC ADC
∠ ∠ ,
即 3
πsin 2 sin 3
x AC
得
θθ
x
θ
x
AC cossin4
3
2sin
2
3
........................................9 分
在 Rt ABC△ 中, = sin sin
AB xAC .............................................................10 分
所以
θ
x
θθ
x
sincossin4
3 ,.............................................................................11 分
解得
4
3cos θ 即 3cos = 4ACB∠ .....................................................................12 分
思路探求 3:作辅助线,过点 C 作 ADCE 于点 E ,构造两个直角三角形,将 AC 用边角来表示,
再将 AC 用 Rt ABC△ 中边角来表示,最后再由等量代换求解即可得.
(2)解法三
过点 C 作 ADCE 于点 E
设 =ACB ∠ , AB x ,
则 2DAC ∠ , 3DC x ........................................................................7 分
在 △Rt CDE 中, xxDDCCE 2
3
3sin3sin ;.........................................8 分
在 △Rt ACE 中,
θθ
x
θ
x
CAE
CEAC cossin4
3
2sin2
3
sin
...................................9 分
在 Rt ABC△ 中, = sin sin
AB xAC .........................................10 分
所以
θ
x
θθ
x
sincossin4
3 ,.........................................................11 分
解得
4
3cos θ 即 3cos = 4ACB∠ .................................................12 分市质检数学(理科)参考解答与评分标准 第 4页 共 12页
18.本小题考查线面垂直的判定与性质、二面角的求解及空间向量的坐标运算等基础知识,考查空间想象
能力、推理论证及运算求解能力,考查化归与转化思想、数形结合思想等,体现基础性、综合性与应
用性,导向对发展数学抽象、逻辑推理、直观想象等核心素养的关注.满分 12 分.
解:解法一:(1)依题意知,因为CD BE^ ,所以 PE BE^ ,·················································1 分
当平面 PBE ^ 平面 ABED 时,
平面 PBE 平面 ABCD BE= , PE Ì 平面 PBE ,
所以 PE ^ 平面 ABCD ,··········································································· 2 分
因为 AB 平面 ABCD ,所以 PE AB^ ,······················································ 3 分
由已知, BCDD 是等边三角形,且 E 为CD 的中点,
所以 BE CD^ , CDAB // ,所以 AB BE^ , ·············································4 分
又 PE BE E = ,所以 AB ^ 平面 PBE ,·····················································5 分
又 AB Ì 平面 PAB ,所以平面 PAB ^ 平面 PBE . ·········································
(2)以 E 为原点,分别以 ED , EB , EP 的方向为 x 轴, y
轴, z 轴的正方向,建立空间直角坐标系 xyzE ,
则 )0,0,0(E , )1,0,0(P , )0,3,0(B , )0,3,2(A ,
)1,0,0(EP , )0,3,2(EA , )0,0,2(BA ,
)1,3,2( PA ,······················································································· 7 分
设平面 PAB 的一个法向量 )(m 111 z,y,x ,平面 PAE 的一个法向量 )(n 222 z,y,x
由
0
0
mPA
mBA 得
03
0
111
1
zy2x
2x ;令 11 y ,解得 31 z , 01 x ,
所以 )30,1,(m ,·····················································································8 分
由
0
0
nEA
nEP 得
03
0
22
2
y2x
z ;令 22 y ,解得 32 x , 02 z ,市质检数学(理科)参考解答与评分标准 第 5页 共 12页
所以 ( 3,-2,0)n , ·················································································9 分
2 2 2 2 2 2
0 2 0 2 7cos , .72 70 1 ( 3) ( 3) ( 2) 0
m nm n
m n
···· 11 分
易得所求二面角为锐角,所以二面角的余弦值为
7
7 .······································· 12 分
解法二:(1)同解法一
(2)由(1)知 PE 平面 ABCD ,且 PE 平面 PAE ,
所以平面 PAE 平面 ABCD .
在 ABE 中,作 BF AE ,垂足 F .
因为平面 PAE 平面 ABCD AE ,BF 平面
ABCD ,
所以 BF 平面 PAE . ············································· 7 分
所以 BF AP .
因为 BP BC AB ,所以 ABP 是等腰三角形.
取 AP 的中点G ,并连接 FG , BG ,则 BG AP . ····························8 分
又 BF BG B ,所以 AP 平面 BFG .
所以 BGF 为二面角 EPAB 的平面角. ·····································9 分
在 RT ABE 中, 2AB , 3BE , 7AE 所以 2 3 2 21
77
BF . ·10 分
同理,在 RT ABP 中, 2AB BP , 2 2AP ,所以 2BG . ··· 11 分
在 RT BFG 中, 14
7GF ,所以 7cos 7
FGBGF BG
.
所以二面角 EPAB 的余弦值为 7
7 . ············································· 12 分
19.本小题主要考查椭圆的几何性质、直线与椭圆的位置关系等基础知识,考查推理论证能力、运算求解
能力等,考查化归与转化思想、数形结合思想、函数与方程思想等,体现基础性、综合性与创新性,
导向对发展逻辑推理、直观想象、数学运算、数学建模等核心素养的关注.满分 12 分.
解法一:(1)由己知得 2 2 1a b ,······················································································1 分
因点 3(1, )2P 在椭圆上,所以 2 2
1 9 14a b
···························································· 2 分
所以 2 24, 3a b ···························································································3 分
所以椭圆 的方程为:
2 2
14 3
x y ······································································ 4 分市质检数学(理科)参考解答与评分标准 第 6页 共 12页
(2)设直线l 的方程为 1
2y x t , ············································································5 分
联立 2 2
1
2
14 3
y x t
x y
,消去 y 得 2 2 3 0x tx t , ·············································· 7 分
在 时, 1 2x x t , 1 2
2 3x x t ······························································8 分
由 1 2 1 23 4 0x x y y ,即 1 2 1 2
1 13 4 02 2x x x t x t
,
所以 2
1 2 1 22 2 0x x t x x t (*). ·······························································9 分
将 1 2x x t , 1 2
2 3x x t 代入(*)式,解得 2 2t ,·····································10 分
由于圆心 O 到直线l 的距离为 2 2 2
5 5
td ,···················································11 分
所以直线l 被圆O 截得的弦长为 2 8 4 152 4 2 4 5 5l d .···························12 分
解法二:(1) 2 2 2 23 32 (1 1) ( 0) (1 1) ( 0) 42 2a ,所以 2a ································· 2 分
所以 2 2 2c 4 1 3b a ·············································································· 3 分
所以椭圆 的方程为:
2 2
14 3
x y ······································································ 4 分
(2)同解法一. ····································································································12 分
20.本小题主要考查等高条形图、独立性检验、分布列与期望等基础知识,考查数据处理能力、运算求解
能力、应用意识等,考查统计与概率思想等,考查数学抽象、数学建模、数据分析等核心素养,体现
基础性、综合性与应用性.
解:(1)根据所给等高条形图,得列联表:
A 材料 B 材料 合计
成功 45 30 75
不成功 5 20 25
合计 50 50 100
A 材料或 B 材料的数据对,给 1 分,全对 2 分市质检数学(理科)参考解答与评分标准 第 7页 共 12页
································································································································ 2 分
2K 的观测值
2100 (45 20 5 30) =1250 50 75 25
k ,························································· 4 分
由于12 6.635 ,
故有 99%的把握认为试验成功与材料有关.································································5 分
(2)生产 1 吨的石墨烯发热膜,所需的修复费用为 X 万元.······································6 分
易知 X 可取 0,0.1,0.2,0.3,0.4,0.5.······························································· 7 分
2
0
2
1 2 20 =2 3 12P X C
,
2
1
2
1 2 40.1 =2 3 12P X C
,
2
2
2
1 2 20.2 =2 3 12P X C
,
2
0
2
1 1 10.3 =2 3 12P X C
,
2
1
2
1 1 20.4 =2 3 12P X C
,
2
2
2
1 1 10.5 =2 3 12P X C
,··························9 分
则 X 的分布列为:
X 0 0.1 0.2 0.3 0.4 0.5
P 1
6
1
3
1
6
1
12
1
6
1
12
修复费用的期望: 1 1 1 1 1 10 0.1 0.2 0.3 0.4 0.5 0.26 3 6 12 6 12E X . 11 分
所以石墨烯发热膜的定价至少为 0.2+1+1=2.2 万元/吨,才能实现预期的利润目标.······· 12 分
21.本小题主要考查导数的综合应用,利用导数研究函数的单调性、最值和零点等问题,考查抽象概括、
推理论证、运算求解能力,考查应用意识与创新意识,综合考查化归与转化思想、分类与整合思想、
函数与方程思想、数形结合思想、有限与无限思想以及特殊与一般思想,考查数学抽象、逻辑推理、
直观想象、数学运算、数学建模等核心素养.满分 12 分.
解:(1)当 0a 时, 2cos xexf x ,········································································ 1 分
记 xfxg ,则 xexg x sin ,
当 0x 时, 1sin1,1 xex ,
所以 0sin xexg x , xg 在 ,0 单调递增,··············································· 2 分
列式 1 分,结果 1 分
最后回答对,无大小比较,不扣分
单位:元,0,1000,2000…也可
22000 元/吨,也可
列式 1 分,结果 1 分
分布列没写,不扣分
概率值没化简不扣分
对 1-3 个,1 分
全对,2 分市质检数学(理科)参考解答与评分标准 第 8页 共 12页
所以 00 gxg ,
因为 0 xgxf ,所以 xf 在 ,0 为增函数;···············································3 分
当 0x 时, 1cos1,1 xex ,所以 02-cos xexf x ,
所以 xf 在 ,0 为减函数.················································································· 4 分
综上所述, xf 的递增区间为 ,0 ,递减区间为 ,0 .······································· 5 分
(2)由题意可得 22cos axxexf x , 00 f .
记 xfxg ,则 axexg x 2-sin .
再令 xexhxgxh x cos, 则 .
下面证明 xexh x cos 在
0,2
有零点:
令 xexxhx x sin, 则 在
0,2
是增函数,所以 02
x .
又 00,02
, ,···················································································· 6 分
所以存在 0,0,2 11
xx ,且当 00,,0,,2 11
xxxxxx , ,
所以 xhx ,即 在 为增函数为减函数,在 0,,2 11 xx
,
又 00,02
hh ,所以 01 xh ,
根据零点存在性定理,存在 0,,2 010
xhxx ················································7 分
所以当 ,0,0,0 xhxx
又 0cos,0 xexhx x ,市质检数学(理科)参考解答与评分标准 第 9页 共 12页
所以 ,xh 即 axexg x 2-sin 在 0,0x 单调递减,在 ,0 单调递增,
所以 aaegxg 212-0sin0 0 .····························································· 8 分
①当
2
1021 aa , , 0 xg 恒成立,所以 xfxg ,即 为增函数,
又 00 f ,所以当 ,0,0,0 xfxx xf 为减函数, ,0,0 xfx , xf 为增
函数, 0x 是 xf 的极小值点,所以
2
1a 满足题意.············································10 分
②当
2
1a , ,02-10 ag 令 0,1)( xxexu x
因为 0x ,所以 01)( xexu ,
故 )(xu 在 ),0( 单调递增,故 0)0()( uxu ,即有 1 xex
故 022sin1222sin2 2 aaaaaeag a ,
又 axexg x 2-sin 在 ,0 单调递增,
由零点存在性定理知,存在唯一实数 ,0,0 mgm , 11 分
当 ,0,,0 xgmx xg 单调递减,即 xf 递减,
所以 00 fxf ,
此时 xf 在 m,0 为减函数,所以 00 fxf ,不合题意,应舍去.
综上所述, a 的取值范围是
2
1a .········································································12 分
(二)选考题:共 10 分。请考生在第 22、23 题中任选一题作答,如果多做,则按所做的第一题计分。
22.选修 4 4 :坐标系与参数方程
本小题主要考查圆的直角坐标方程与极坐标方程的互化,直线的参数方程及参数的几何意义、直线与
圆的位置关系等基础知识,考查推理论证能力与运算求解能力,考查函数与方程思想、转化与化归思
想、数形结合思想,体现基础性与综合性,导向对发展直观想象、逻辑推理、数学运算等核心素养的
关注.满分 10 分.
解:(1)因为
,
4 3
x t
y t
,所以l 的普通方程为 3 4 0x y ,···········································1 分
又 2 2 2cos , sin ,x y x y ,
l 的极坐标方程为 3 cos sin 4 0 ,·························································· 3 分市质检数学(理科)参考解答与评分标准 第 10页 共 12页
C 的方程即为 2 2 2 0x y y ,对应极坐标方程为 2sin . ································· 5 分
(2)由己知设 1 2( , ), ( , )A B ,则 1
4 ,
3 cos sin
2 2sin , ······················· 6 分
所以,
||
||
OA
OB 2
1
| | 1 12sin ( 3 cos sin ) [ 3sin 2 cos2 1]| | 4 4
OA
OB
·················7 分
1[2sin(2 ) 1]4 6
······························································· 8 分
又 5
6 12
, 226 6 3
,
当 2 6 6
,即
6
时,
||
||
OA
OB 取得最小值 1
2
;················································· 9 分
当 2 6 2
,即
3
时,
||
||
OA
OB 取得最大值 3
4
.················································10 分
所以,
||
||
OA
OB 的取值范围为 1 3[ , ]2 4
.········································································ 10 分
23.选修 4 5 :不等式选讲
本小题主要考查绝对值不等式的解法、不等式解集的概念、绝对值的意义等基础知识,考查抽象概括
能力、运算求解能力,考查分类与整合的思想,转化与化归的思想,体现基础性与综合性,导向对发
展逻辑运算、数学运算、直观想象等核心素养的关注.满分 10 分.
解法一 :(1)
.2
1,2
13
2
1
2
1,2
3
2
1,2
13
xx
xx
xx
xf ,
,
·········································································· 2 分
当
2
1x 时, 22
1
fxf ,
当
2
1
2
1 x , 12
1
fxf ,
当
2
1x 时, 12
1
fxf ,········································································4 分
所以 1min xfm ·························································································5 分
对 1 个给 1 分,全对 2 分
对 1 个给 1 分,全对 2 分市质检数学(理科)参考解答与评分标准 第 11页 共 12页
补充:解法二 :(1)
.2
1,2
13
2
1
2
1,2
3
2
1,2
13
xx
xx
xx
xf ,
,
································································· 2 分
如图··································································································4 分
当 1
2x 时, 1min xfm ·································································5 分
解法三 :(1) 1 1 1 1 1 1( ) 2 2 2 2 2 2
≥f x x x x x x x ································1 分
11 12
≥x ························································································2 分
当且仅当
1 1 02 2
1 =02
≤x x
x
即 1= 2x 时,等号成立. ········································· 4 分
(列式 1 分,x 值 1 分,或直接给出 x 值,2 分)
当 1
2x 时, 1min xfm ··········································································· 5 分
解法一:(2)由题意可知,
baccabcab 111 ,·····························································6 分
因为 0, 0, 0 a b c , 所以要证明不等式 9ab bc ca a b c
,
只需证明 9111 cbabac
)( ,·································································7 分
因为 9313111 33 abcabccbabac
)( 成立,·········································· 9 分
所以原不等式成立.························································································· 10 分
两个基本不等式各 1 分
对 1 个给 1 分,全对 2 分市质检数学(理科)参考解答与评分标准 第 12页 共 12页
解法二:(2)因为 03,0,0,0 3 222 cbacabcabcba 所以 ,······································ 6 分
033 abccba ,·················································································· 7 分
又因为 1abc ,
所以 933 3 2223 cbaabcacbcabcba ,········································· 8 分
9 ≥ab bc ac a b c ············································································ 9 分
所以 9ab bc ca a b c
,原不等式得证.····················································· 10 分
补充:解法三:(2)由题意可知,
baccabcab 111 ,····················································6 分
因为 0, 0, 0 a b c , 所以要证明不等式 9ab bc ca a b c
,
只需证明 1 1 1 9
≥a b ca b c
,······················································ 7 分
由柯西不等式得:
21 1 1 1 1 1+ + 9
≥a b c a b ca b c a b c
成
立,·····································································································9 分
所以原不等式成立.················································································ 10 分
柯西 2 分
踩空回补