f（x）=cos（π-x）sin（π/2+x）+根号3sinxcosx= -cosx cosx + 根号3sinxcosx= -cos^2x + 根号3sinxcosx= -(1+cos2x)/2 + 根号3/2 sin2x = 根号3/2 sin2x -1/2 cos2x - 1/2= sin2xcosπ/6-cos2xsinπ/6 - 1/2= sin(...这类题目是不是要把f（x）化简成一个cos或sin？？然后再求？？是的~