sin(x+π/3)＋2sin(x-π/3)－√3 cos(2π/3-x) ＝sin(x+π/3)＋2sin(x-π/3)＋√3 cos(x+π/3) ＝[sin(x+π/3)＋√3 cos(x+π/3)]＋2sin(x-π/3) ＝2sin(x+2π/3)＋2sin(x-π/3) ＝2sin(π/3-x)＋2sin(x-π/3) ＝0...