1: \(-3\cdot\sin^2x\cdot cos^2x\)
\(=-3\cdot\left(\sin x\cdot cosx\right)^2\)
\(=-3\cdot\left(\frac12\cdot2\cdot\sin x\cdot cosx\right)^2\)
\(=-3\cdot\left\lbrack\frac12\cdot\sin2x\right\rbrack^2=-3\cdot\frac14\cdot\sin^22x=-\frac34\cdot\sin^22x\)
Giải các phương trình sau
1) 4cos2x - 6sin2x + 5 sin2x - 4 =0
2) \(\sqrt{3}\)cos2x + 2sinxcosx - \(\sqrt{3}\)sin2x - 1 =0
3) 2sin22x - 3sin2x.cos2x + cos22x = 2
4) 4cos2 \(\dfrac{x}{2}\)+\(\dfrac{1}{2}\)sinx +3sin2\(\dfrac{x}{2}\) = 3
Giải các phương trình sau
1) 4cos2x - 6sin2x + 5 sin2x - 4 =0
2) \(\sqrt{3}\)cos2x+ 2sinxcosx - \(\sqrt{3}\)sin2x - 1 =0
3) 2sin22x - 3sin2x.cos2x + cos22x = 2
4) 4cos2\(\dfrac{x}{2}\)+\(\dfrac{1}{2}\)sinx+3sin2\(\dfrac{x}{2}\)=3
Helppp meee.. Hic hic :<
\(cosx\sqrt{\frac{1}{cosx}-1}+cos3x\sqrt{\frac{1}{cos3x}-1}=1\)
Giải pt:
a) \(sinx+\frac{1}{sin2x}=cosx+\frac{1}{cosx}\)
b) \(sin^2x+\frac{sin2x}{2}=1\)
c) \(\frac{1}{1+cos^2x}+\frac{1}{1+sin^2x}=\frac{16}{11}\)
Giải PT:
\(\dfrac{1}{sinx}+\dfrac{1}{sin2x}+\dfrac{1}{sin4x}+\dfrac{1}{sin8x}=0\) trên khoảng \(\left(0;\dfrac{3\pi}{2}\right)\)
1) GTNN va GTLN cua ham so y=cos\(\sqrt{x}\) la: (giai ra nua nha)
A. 0 va 4 B. -4 va 4 C. 0va 1 D. -1 va 1
Giải pt: a)sin^3x+cos^3x+1=3sinxcosxb) (1+cosx)×(1+sinx)=2
Giải phương trình sau: \(\cot x-1=\dfrac{\cos2x}{1+\tan x}+\sin^2x-\dfrac{1}{2}\sin2x\)
Giúp mình với mn...
1)cos2x+cos22x+cos23x+cos24x=2
2) (1-tanx) (1+sin2x)=1+tanx
3) tan2x=sin3x.cosx
4) tanx +cot2x=2cot4x
5) sinx+sin2x+sin3x=cosx+cos2x+cos3x
6)sinx=√2 sin5x-cosx
7) 1/sin2x + 1/cos2x =2/sin4x
8) sinx+cosx=cos2x/1-sin2x
9)1+cos2x/cosx= sin2x/1-cos2x
10)sin3x+cos3x/2cosx-sinx=cos2x
