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高三数学(理科)答案第 1 页 共 12 页
二○一七届高三模拟考试
数学(理科)参考答案及评分标准 2017.3
一、选择题:本大题共 10小题,每小题 5分,共 50分.
BDAC CACB AD
二、填空题:本大题共 5小题,每小题 5分,共 25分.
11. 24 12. 2 13. 2 14. 2 3 15. 1( , e )
e
−∞ − −
三、解答题:本大题共 6小题,共 75分.
16.(1)由题意,
π( ) sin(2 ).
3
f x x= − ········································································ 2分
令
π π2 π
3 2
x k− = + , .k ∈ Z ··············································································· 4分
解得 ( )y f x= 图象的对称轴方程为 π 5π
2 12
kx = + , .k ∈ Z ································· 5分
(2)由
3( )
2
f A = ,得 πsin(2 )
3
3 .
2
A − =
由0 πA< < ,得 π π 5π2 ( , ).
3 3 3
A − ∈ −
所以
π π2
3 3
A − = ,或 π 2π2 .
3 3
A − = 所以 π
3
A = ,或 π .
2
A = ······························· 7分
由正弦定理,得
sin sin
b a
B A
= ,所以
sinsin .b AB
a
=
当
π
3
A = 时,
2 3 3
sin 13 2sin
2 2
b AB
a
×
= = = ;·················································· 9分
当
π
2
A = 时,
2 3 1sin 33sin .
2 3
b AB
a
×
= = = ·····················································11分
综上, sin B的值为 1
2
,或
3 .
3
·········································································· 12分
17.解:(1)记M 与 1B 、 2B 、 3B 进行对抗赛获胜的事件分别为 A、B、C,M 至少获
胜两场的事件为D,则 4( )
5
P A = , 2( )
3
P B = , 1( )
2
P C = .
则 .D ABC ABC ABC ABC= + + + ········································································· 1分
由于事件 A, B,C相互独立,所以
高三数学(理科)答案第 2 页 共 12 页
( ) ( ) ( ) ( ) ( )P D P ABC P ABC P ABC P ABC= + + +
4 2 1 4 2 1 4 2 1 4 2 1 11(1 ) (1 ) (1 ) .
5 3 2 5 3 2 5 3 2 5 3 2 15
= × × + × × − + × − × + − × × = ··············· 5分
因为
11 7
15 10
> ,所以M 会入选下一轮. ······························································ 6分
(2)M 获胜场数 X 的可能取值为 0,1, 2, 3.
则
1 1 1 1( 0) ( )
5 3 2 30
P X P ABC= = = × × = ;
4 1 1 1 2 1 1 1 1 7( 1) ( ) ( ) ( )
5 3 2 5 3 2 5 3 2 30
P X P ABC P ABC P ABC= = + + = × × + × × + × × = ;
7( 2) ( ) ( ) ( )
15
P X P ABC P ABC P ABC= = + + = ;
4 2 1 4( 3) ( ) .
5 3 2 15
P X P ABC= = = × × = ······