2018高一数学竞赛答案.docx
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- 2021-05-09 发布|
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- 4页
2018
1.D 2 C 3.A
4.B
5. D
6 B
7. D
8. C
9.B 10. A 11.B 12.D
13. 3
14.
x
2 3x
4 y
10 0
15. 3
16.34
2
171
c
c
b b
(a
b)
a
2R
2R
2R
c2
b2
a2
ab
..4
a 2
b2
c2
ab
cosC
1 , C
3
2
(2) c2
a2
b2
2ab cos
3
25
a2
b2
ab..6
a 2
b2
25
ab
2ab
ab
25
S
1
absin C
25
3
( a
b时取得最大值）..10
2
4
18.(1)la
2
0. a
2.
lx
y
0.
2
la
2 a
1
2
a
2
a,a 0
a
1
lx
y 2
0.
5
lx
y
0. x y
2
0.
6
2lM ( 2
a ,0), N (0,2
a),
a 1
a
1,S
1
2
a
1
a 1
1 2
OMN
2
a
(2
a)
a
1
1
2
= 1
a
1
1
2
1
2
(a 1)
1
2
2
2
a
1
2
a
1
10
a
1
1 , a
0
11
a
1
lx
y
2
0.
12
试卷第 1页，总 4页
19:
(1)
m
(sin 2wx, cos2wx),
n (cos , sin ),
f ( x)
m n sin 2wx cos
cos2wx sin
sin(2wx
)
T
5
6
,T
, w 1
..2
4
12
P(
,1)y
sin(2x
)sin(2
6
) 1
6
6
2k , (k
Z )
,
6
4
2
f (x)
sin(2x
), (x R)5
6
2f (C )
1,sin( 2C
)
1,
2
6
0 C π
C
3
7
CA CB
3 ,ab cos C
3
2
2
ab=3
9
c=3
12
20.1 an
2
4sn
2