cospi/6cosx-sinpi/6sinx=cos3x
cos(pi/6+x)=cos3x
cos(pi/6+x)-cos3x=0
-2sin(pi/6+x-3x/2sinp/6+x+3x/2=0
-2sin(pi/12-x)sinpi/12+2x)=0
2sin(x-pi/12)sin(pi/12+2x)=0
sin(x-pi/12)=0
x-pi/12=pin
x=pi/12+pin n €a
sin(pi/12+2x)=0
pi/12+2x=pin
2x=-pi/12 +pin
x=-pi/24+pin/2 n€z
