F4 Maths Question Pls Help~!

Pls find the general solutions
1)sin3x+cos2x=0
2)cosxcos3x=cos7xcos5x
3)sin6xsinx=cos3xcos4x
4)16cos^4 x=1
5)tanx=cotx
6sin(x+40degrees)sin(x-40degrees)=3/5
7)sin7x-sinx=sin3x
8)cos3x=cos2xcosx
sin9x+sin5x+sin^2 x=1