Sin7xcos3x-cos7xsin3x=-1
Sin(x-y)=sinxcosy-cosxsiny sin7xcos3x-cos7xsin3x=-1 sin(7x-3x)=-1 sin4x=-1 4x=3pí/2+2k.pí x=3pí(8+k.pí/2, k=0,1,-1,2,-2,.....