\(cos^2x-sin^2x=0\)\(\Rightarrow cos2x=0\) \(\Rightarrow2x=\dfrac{\pi}{2}+k\pi\)
\(\Rightarrow x=\dfrac{\pi}{4}+k\dfrac{\pi}{2}\)
Giải các phương trình sau:
1) sin2x + sin23x - 3cos22x = 0
2) sin22x + sin24x = sin26x
3) cos4x - 5sin4x = 1
4) sin24x + sin23x = cos22x +cos2x với x∈(0;π)
5) 4sin3x - 1 = 3 - √3cos3x
6)sin2x = cos22x + cos23x
Giải các phương trình sau :
a) \(2\cos^2x-3\cos x+1=0\)
b) \(25\sin^2x+15\sin2x+9\cos^2x=25\)
c) \(2\sin x+\cos x=1\)
d) \(\sin x+1,5\cot x=0\)
\(sin^4x-cos^2x=1\\ \dfrac{3}{cos^2x}+2\sqrt{3}.tgx-6=0\)
1) Cos^4x-sin^4x+5cosx+3=0
2) 3cos^2x+cos^2x×sinx=8(1+sinx)
1)\(sin^23x.cos2x+sin^2x=0\)
2)
\(cos^23x+cos^22x=sin^2x\)
3)
\(\frac{1}{4}+cos^2\frac{x}{3}=\frac{1}{2}sin^2\frac{x}{2}\)
4)
\(sin^23x-sin^22x-sin^2x=0\)
5)
\(2cos^2x=3sin^25x+2\)
6) 3cosx+2cos2x-cos3x=2sinxsin2x-1
7) \(sinx+cosx=\sqrt{2}\left(2-sin^32x\right)\)
Giải phương trình sau:
a) $\tan ^2x+4\cos ^2x+7=4\tan x+8\cot x$
b) $6\sin ^2x+2\cos ^2x-2\sqrt{3}\sin 2x=14\sin \left(x-\frac{\pi }{6}\right)$
Giải phương trình:
\(\left(sin^2x+\frac{1}{sin^2x}\right)^2+\left(cos^2x+\frac{1}{cos^2x}\right)^2=\frac{7}{2}-sin^2y+2siny\)
Giải phương trình:
\(\left(sin^2x+\frac{1}{sin^2x}\right)^2+\left(cos^2x+\frac{1}{cos^2x}\right)^2=\frac{7}{2}-sin^2y+2siny\)
\(\sqrt{2}sin\left(2x-60^0\right)-2sin\left(x-30^0\right)=\sqrt{2}cos\left(2x-60^0\right)\)
