sin3x*sin^2x-sin3x*cos^2x=0

sin3x(sin^2x-cos^2x)=0

-sin3x(cos^2x-sin^2x)=0

-sin3x=0                                         cos^2x-sin^2x=0

sin3x=0                                                        cos2x=0

3x=пk, k принадлежит Z                              2x=п/2 + пk

                                                                      x=п/4+пk/2,  k принадлежит Z