Question

已知:向量m=(sinx,-1) n=(根号3cosx,-1/2)设f(x)=(m+n)m-1

Answer 1

f(x)=(m+n)m-1

=m²+nm -1

=sin²x+1+√3sinxcosx+1/2 -1

=(1-cos2x)/2+(√3/2)sin2x +1/2

=(√3/2)sin2x -(1/2)cos2x

=sin(2x-π/6)

即 f(x)=sin(2x-π/6)