tan(3x/2)-tan(x/2) = [sin(3x/2)/cos(3x/2) - sin(x/2)/cos(x/2)]= (sin3x/2 cosx/2 - con3x/2 sinx/2) / cos3x/2 cosx/2其中：(sin3x/2 cosx/2 - con3x/2 sinx/2) = [(sin2x+sinx)-(sin2x-sinx)]/2 = sinx所以：ta...