Bài 1 : Giải các phơng trình sau
1 cos2x+3sinx=2 ;2 4sin4 x+12 cos2 x=7; 3 25sin2x+100 cosx=89
4 sin 24 x+cos 24 x=sin 2 cos2x x ;5. + =
−
tan 2
cos
x
x ,7,2sin2x – cos2x - 4sinx + 2 = 0;8,9cos2x - 5sin2x - 5cosx + 4 = 0 9) 5sinx(sinx - 1) - cos2x = 3;10)cos2(3x +
2
π ) – cos23x – 3cos(
2
π - 3x) + 2 = 0
11;cos2x + sin2x + 2cosx + 1 = 0;12; 3cos2x + 2(1 + 2 + sinx)sinx – (3 + 2 ) = 0
sin
3
2 = gx+
x
cos
2 cos 3 9 sin 6 2
sin
=
−
− +
x
x x
1 1
2 sin
) 2 (sin
sin 3 ) sin 2 (cos
−
+ +
+
x
x x x
x x
Bai 2Chuyên Đề PT bậc nhất đối với Sin và cos
1) 3cos3x+sin3x= 2 ;2,cos7xcos5x− 3sin2x=1−sin7xsin5x
7
6
; 5
2
∈ của PT:cos7x− 3sin7x=− 2
4) 2 2(sinx+cosx)cosx=3+cos2x;
Bai 3:Chuyên Đề : PT đcấp bậc 2 đối với sin và cos
1) sin2x + 2sinxcosx + 3cos2x - 3 = 0 ;2) sin2x – 3sinxcosx + 1 = 0
3) 4 3 sinxcosx + 4cos2x = 2sin2x + 5/2
2 cos(
) 2
5 sin(
2 ) 3
(
sin
2
3 ( sin
5)[ĐHAN_98]a
x x
x
cos
1 cos
sin
x x
x
cos
1 cos
6 sin
6) cos2x – 3sinxcosx – 2sin2x – 1 = 0
7) 6sin2x + sinxcosx – cos2x = 2
1)[ĐHBKHN_96] sin4x + cos4x = cos2x;2)[ĐH Huế_99] sin6x + cos6x = 7/16
3) sin6x + cos6x = sin 2x
4
6)[ĐHQG_98] cos6x – sin6x =
8
13cos22x;7)[ĐHCĐ_01]
x x
x
sin 2 1 ) 2 ( cos ) 2 (
Bai 5: Chuyên Đề 9: sử dụng ct hạ bậc
sin x+sin 2x−sin 3x=0
2
16
5) cos2x + cos22x + cos23x = 3/2;6)cos2x + cos22x + cos23x = 1
7)[ĐH Huế] sin2x + sin22x + sin23x = 3/2 ;8)[ĐHY_98] sin23x – sin22x – sin2x = 0
9)[ĐHQG_98] sin2x = cos22x + cos23x
10)[ĐH_B02]sin23x – cos24x = sin25x – cos26x ;11)cos2x + cos22x + cos23x + cos24x = 2
12) cos2x + cos22x + cos23x + cos24x = 3/2
C – Phơng trình biến đổi về tích
Bài 6 : Giải phơng trình
1 cosx+cos 2x+cos3x+cos 4x=0 ;2 cosx+cos3x+2cos5x=0
3) sinx + sin2x + sin3x = 1 + cosx + cos2x ;4) sinx + sin2x + sin3x = cosx + cos2x + cos3x
5)[ĐH Nông Lâm TPHCM_01]:1 + cosx + cos2x + cos3x = 0
6)[HVQHQT_99] cosx + cos2x + cos3x + cos4x = 0
7)[ĐHSP Vinh_97] sinx + sin2x + sin3x + sin4x + sin5x + sin6x = 0 8)[ĐH Đà Nẵng_B97] sin3x – sinx + sin2x = 0
Trang 27) cos10x – cos8x – cos6x + 1 = 0 ;8)[HVQHQT_00] cosx + cos3x + 2cos5x = 0
9)[ĐHNTHN_97] 9sinx + 6cosx – 3sin2x + cos2x = 8
10)[ĐHNT TPHCM_00]1 + sinx + cos3x = cosx + sin2x + cos2x
12) (2sinx – 1)(2sin2x + 1) = 3 – 4cos2x
13)[ĐHYHN_96] (cosx – sinx)cosxsinx = cosxcos2x
14)[ĐHHH_00] (2sinx + 1)(3cos4x + 2sinx – 4) + 4cos2-x = 3
15)[ĐH Đà Nẵng_99] cos3x – sin3x = sinx – cosx
17)[ĐHCSND_00] cos3x + sin3x = sin2x + sinx +cosx
18)[HVQY_00] cos2x + sin3x + cosx = 0
19)[HVNH_99] cos3x + cos2x + 2sinx – 2 = 0
20)[HVNH TPHCM_00] sinx + sin2x + cos3x = 0
Chuyên Đề 13: sd CT biến đổi tích thành tổng
3) sin2x + sin2xsin4x + sin3xsin9x + sin4xsin16x = 1