Question

[D. Việt]

CÁC BẠN GIÚP MÌNH VỚI Ạ ^_^

1)\(\sin^2x+\sin^22x+\sin^23x=\frac{3}{2}\)

2)  \(\cos^2x+\cos^22x+\cos^23x=1\)

3)  \(\cos^2x+\cos^22x+\cos^23x+\cos^24x=2\)

4)  \(\sin2x=1+\sqrt{2}\cos x+\cos2x\)

5)  \(\sin x\left(1+\cos x\right)=1+\cos x+\cos^2x\)

6)  \(\left(2\sin x-1\right)\left(2\cos2x+\sin2x+1\right)=3-4\cos^2x\)

7)  \(\sin x+\sin2x+\sin3x=\sqrt{2}\left(\cos x+\cos2x+\cos3x\right)\)

8)  \(\cos5x\cos x=\cos4x\cos2x+3\cos^2x+1\)

9)  \(\sin7x+\cos^22x=\sin^22x+\sin x\)

10)   \(\sin2x+\left(1+2\cos3x\right)\sin x-2\sin^2\left(2x+\frac{\pi}{4}\right)=0\) 

11)  \(\sqrt{3}\cos5x-2\sin3x\cos2x-\sin x=0\)

12)  \(4\cos\frac{5x}{2}\cos\frac{3x}{2}+2\left(8\sin x-1\right)\cos x=5\)