Question

(cos 8x-cos 6x) / (sin 8x+ sin 6x)

Answer 1

(cos 8x-cos 6x) / (sin 8x+ sin 6x)=
=-2sin(14x/2)sin(2x/2) / 2sin(14x/2)cos(2x/2)=-2sin 7x*sin x / 2sin 7x*cos x=
=-sin x / cos x=-tg x.