$1. 1/sin2 x = cotx +3$
$2. cos2 (3x+ \pi/2 ) - cos23x - 3cos(\pi/2 - 3x ) +2 = 0 $
$3. \sqrt{3}/sin2 x = 3cotx + \sqrt{3} $
$4.4\cos 5x.\sin x - 4\sin 5x = \sin24x$
$5. \frac{(2-\sqrt{3}cosx - 2sin2 (x/2 - \pi /4) }{2cosx - 1} = 1$
Mọi người giúp đỡ nhé!