(SINX COS ) 4(COSX X SIN ) SIN2X X 4 0 X 4 K ; X K2...
2) 2)
(sin
x
cos ) 4(cos
x
x
sin ) sin2
x
x
4
0
x
4
k
;
x k
2 ;
x
3
k
2
2
Câu III:
(sin
4
x
cos )(sin
4
x
6
x
cos )
6
x
33
7
cos4
x
3
cos8
x
64 16
64
I
33
128
.
.
1
Câu IV: Đặt V
1
=V
S.AMN
; V
2
=V
A..BCNM
; V=V
S.ABC
;
V
SM SN
SM
(1)
V
1
SB SC
SB
V
V
2
3
3
2
;
4
4a
SM
AM
a SM=
V
V (2)
5
5
5
V
1
V
2
2
SB
V
2
a
3
. 3
V
1
S
.
SA
3
. 3
ABC
a
3
3
5
Câu V:
a
4
b
4
2
a b (1); b
2 2
4
c
4
2
b c (2); c
2 2
4
a
4
2
c a (3)
2 2
a
4
b
4
c
4
abc a b c
(
)
a
4
b
4
c
4
abcd abc a b c d
(
)
1
1
(4)
abc a b c d
(
)
đpcm.
a
4
b
4
c
4
abcd
Câu VI.a: 1) A(3; 1), B(5; 5)
(C):
x
2
y
2
4
x
8
y
10 0
( ) :
1