1 + sin\(\dfrac{x}{2}\)sinx - cos\(\dfrac{x}{2}\)sin²x = 2cos²\(\left(\dfrac{\pi}{4}-\dfrac{x}{2}\right)\)

cos²x + cos²2x + cos²3x = 1

sin²2x - sin²8x = sin\(\left(\dfrac{17\pi}{2}+10\pi\right)\)

4cos\(\dfrac{5x}{2}\)cos\(\dfrac{3x}{2}\)+2(8sinx - 1)cosx = 5

sin²x + sin²2x + sin²3x = \(\dfrac{3}{2}\)

cosx.cos3x - sin2x.sin6x - sin4x.sin6x = 0

\(\sqrt{3}\)cos6x - 2sin4x.cos2x - sin2x = 0

Giải phương trình lượng giác

cos3x.cosx = cos2x

sinx.sin5x = sin2x.sin3x

Giải phương trình:

3sin2x + 2cos2x = 3

a) cos2x - sinx + cosx = 0

b) 2cos³x + sinx + cos2 = 0

sinx + sin2x + sin3x = 1 + cosx + cos2x

cos3x + sin3x + cosx - sinx = \(\sqrt{2}\)cos2x

sinx + sin2x + sin3x = cosx + cos2x + cos3x

2sin²2x + sin6x - 1 = sin2x

sin2x + sin6x + 2sin²x - 1 = 0

sin4x + sin2x - 2cos²x = 0

sinx + sin5x + 1 - cos²x = 0

cosx + cos2x + cos3x + 1 = 0