Cos(3П/2+x)cos3x-cos(П-x)sin 3 x=-1

Question

Cos(3П/2+x)cos3x-cos(П-x)sin 3 x=-1

Answer 1

Sin xcosx-(-cosx)*sin 3x =-1
sin (4x) =-1
4x=3п/2+2kп
х=3п/8
у=-1