1)căn2 cos( x/5 – pi/12) – căn6 sin( x/5 – pi/12) = 2 sin( x/5 + 2pi/3) - 2sin( 3x/5 + pi/6)

2)sin4x(1/4 sin4x – 3/2 sin2x +3) + 5 sin^2 2x – 4sin2x -9 + cos2x( 9 -sin4x)=0

3)2cos^3 x - sin2x( sinx + cosx)+ cos2x ( sinx + căn2 ) – căn2 ( sin2x +1) -2cox – sinx=0

4)2sin^2 ( x- pi/4)= 2sin^2 x- tanx

5)9sinx + 6sin -3 sin2x + cos2x=8

6)2cos6x + 2 cos4x – căn3 cos2x= sin2x+ căn3

7)2cos3xcosx + căn3 ( 1+ sin2x) = 2căn3 cos^2 ( 2x +pi/4)

8)1/ tanx + cot2x = căn2 (cosx – sinx) / cotx -1