Question

已知函数f(x)=2cosxsin(x+π\3)-根号3\2,若三角形ABC的三边a,b,c满足b^2=ac,且边b所对

Answer 1

f(x)=sinxcosx+根号3倍(cosx)^2-根号3=(1/2)sin2x+(根号3/2)cos2x=sin(2x+派/3).cosB=(a^2+c^2-b^2)/2ac=(a^2+c^2-ac)/2ac>=ac/2ac=1/2,所以1/2