4sin^2 3x cos^2 3x + 8sin^2 3x=0 4sin^2x(cos^2 3x+2)=0 4sin^2 3x=0 sin^2 3x=0 1-cos6x/2=0 cos6x=1 6x=2pn x=pn/3 sin^2 2x+cos4x=0 sin^2x+cos^2 2x-sin^2 2x=0 cos^2 2x=0 1+cos4x/2=0 cos4x=-1 4x=p+2pk x=p/4+pk/2