\(3sinx-4sin^3x-4cos^3x+3cosx+\left(sinx+cosx\right)^2=0\)
\(\Leftrightarrow3\left(sinx+cosx\right)-4\left(sinx+cosx\right)\left(1-sinx.cosx\right)+\left(sinx+cosx\right)^2=0\)
\(\Leftrightarrow\left(sinx+cosx\right)\left(3-4+4sinx.cosx+sinx+cosx\right)=0\)
Xét \(sinx+cosx+4sinx.cosx-1=0\)
Đặt \(sinx+cosx=t\) (\(\left|t\right|\le\sqrt{2}\)) \(\Rightarrow2sinx.cosx=t^2-1\)
\(\Rightarrow2\left(t^2-1\right)+t-1=0\)
sinx - sin3x + sin5x =0
sin2x + sin22x = sin23x
cos3x - cos5x = sinx
sin3x + sin5x + sin7x = 0
sinx + sin2x + sin3x - cosx - cos2x - cos3x = 0
sin3x(cosx - sin3x) + cos3x(sinx - cos3x)= 0
Giải các phương trình :
a) \(\cos3x-\sin2x=0\)
b) \(\tan x\tan2x=-1\)
c) \(\sin3x+\sin5x=0\)
d) \(\cot2x\cot3x=1\)
Giải các phương trình sau:
1. tan2x+3= (1+√2 sin x)(tan x+ √2 cos x)
2. (1- cos x. cos2x )/ sin2x - 1/ cos x= 4 sin2x - sin x-1
3. sin3x + 2 cos3x+ cos2x - 2sin2x - 2sinx-1=0
HELPING NOW!!!
Giair phương trình lượng giác sau:
1) cosx - cos2x +cos3x = 0
2) cos2x - sin2x = sin3x + cos4x
3) cos2x + 2sinx - 1 - 2sinxsosx = 0
4) 1+ sinx - cosx = sin2x - cos2x
5) \(\sqrt{2}\) sin (2x+\(\dfrac{\pi}{4}\)) - sinx - 3cosx +2 =0
6) sin2x + 2cos2x = 1+sinx - 4cosx
sin3x - cos3x +2sin2x +1 =0
•Sin3x - sin5x = sin2x
•Cosx + cos2x + cos3x = -1
•Sin2x + sin22x +sin23x + sin24x = 2
•1 + 2 sinxcos2x = sinx + cos2x
•Tan3x - tanx = sin2x
•(1-tanx)(1+sin2x) = 1+ tanx
\(\frac{ }{ }\)
giải các phương trình : a) \(\sin x+\sin2x+\sin3x=\cos x+\cos2x+\cos3x\) ; b) \(\sin x=\sqrt{2}\sin5x-\cos x\) ; c) \(\frac{1}{\sin2x}+\frac{1}{\cos2x}=\frac{2}{\sin4x}\) ; d)
\(\sin x+\cos x=\frac{\cos2x}{1-\sin2x}\)
Giải các phương trình sau:
a, cos3x-4cos2x+3cosx-4=0, ∀x∈[0;14]
b, (2cosx-1)(2cos+cosx)=sin2x-sinx
c, cos3x+cos2x+1+sin2x+cos2x=0
