f(x)=sinx+sin(x+π/2)=sinx+sinxcosπ/2+cosxsinπ/2=sinx+cosx亲 我大半夜的纠结的就是这段sinx+sinxcosπ/2+cosxsinπ/2=sinx+cosx，你还偏偏就发给我这段cosπ/2=0. sinπ/2 =1=>sinx+sinxcosπ/2+cosxsinπ/2=sinx+0*sinx+1*cosx=sinx+cosx