sin(10x) sin(2x) = sin(8x) sin(4x)[cos(10x-2x)-cos(10x+2x)]/2=[cos(8x-4x)-cos(8x+4x)]/2cos(8x)-cos(12x)=cos(4x)-cos(12x)cos(8x)=cos(4x)8x=4x+2pi*k => x=pi*k/2и8x=-4x+2pi*n => x=pi*n/6
sin(10x) sin(2x) = sin(8x) sin(4x)
[cos(10x-2x)-cos(10x+2x)]/2=[cos(8x-4x)-cos(8x+4x)]/2
cos(8x)-cos(12x)=cos(4x)-cos(12x)
cos(8x)=cos(4x)
8x=4x+2pi*k => x=pi*k/2
и
8x=-4x+2pi*n => x=pi*n/6