Giải phương trình: sin(2x - pi/4) = cos(pi/3 - x); cos2x - 3sinx - 2 = 0; 2tanx - 2cotx - 3 = 0

1) sin(2x-pi/4)=cos(pi/3-x)
2) cos2x-3sinx-2=0
3) 2tanx-2cotx-3=0
4) cos4x-cos2x+2sin^2x=0
5) sin^2x-cosx+1=0
6) 4/cos^2 2x+tan2x-7=0
7) (2sinx-cosx)(1+cosx)=sin^2x