cos(pi/3)cos2x+sin(pi/3)sin2x=1
1/2[cos(pi/3+2x)+cos(pi/3-2x)]+1/2[cos(pi/3-2x)-cos(pi/3+2x)]=1
cos(pi/3-2x)=1
pi/3-2x=2pik
2x=pi/3+2pik
x=pi/6+pik kєZ
cos(pi/3)cos2x+sin(pi/3)sin2x=1
1/2[cos(pi/3+2x)+cos(pi/3-2x)]+1/2[cos(pi/3-2x)-cos(pi/3+2x)]=1
cos(pi/3-2x)=1
pi/3-2x=2pik
2x=pi/3+2pik
x=pi/6+pik kєZ