\(\Leftrightarrow sin5x=-sin3x\)
\(\Leftrightarrow sin5x=sin\left(-3x\right)\)
\(\Leftrightarrow\left[{}\begin{matrix}5x=-3x+k2\pi\\5x=\pi+3x+k2\pi\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}8x=k2\pi\\2x=\pi+k2\pi\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{k\pi}{4}\\x=\dfrac{\pi}{2}+k\pi\end{matrix}\right.\) (\(k\in Z\))
sinx - sin3x + sin5x =0
sin2x + sin22x = sin23x
cos3x - cos5x = sinx
sin3x + sin5x + sin7x = 0
sinx + sin2x + sin3x - cosx - cos2x - cos3x = 0
Giải các phương trình sau
a. Cosx+cos2x+cos3x+cos4x=0
b. Sinx+sin3x+sin5x+sin7x=0
Giải các phương trình :
a) \(\cos3x-\sin2x=0\)
b) \(\tan x\tan2x=-1\)
c) \(\sin3x+\sin5x=0\)
d) \(\cot2x\cot3x=1\)
Giải phương trình lượng giác:
1) 2cos3x + 1 = 0 , 0o ≤ x ≤ 180o
2) \(sin\frac{x}{2}-\sqrt{3}+cos\frac{x}{2}=\sqrt{3}\)
3) \(\sqrt{3}\left(cos5x+sin3x\right)=cos3x-sin5x\)
•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
\(\frac{ }{ }\)
sin3x(cosx - sin3x) + cos3x(sinx - cos3x)= 0
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 : 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 pt:
\(sin5x-cos3x=0\)
