Question

已知f(x)=sin(P/2+x)cosx-sinxcos(P-x)

Answer 1

(1)f(x)=sin(Pi/2+x)cosx-sinxcos(Pi-x)=cosxcosx+sinxcosx=(cos(2x)+1)/2+sin(2x)/2=(sin(2x)+cos(2x))/2+1/2=( sin(2x)*sqrt(2)/2+cos(2x)*sqrt(2)/2 )/sqrt(2)+1/2=( sin(2x)*cos(Pi/4)+cos(2x)*sin(Pi/4) )/sqrt...