过点A作BC边上的高AD∵∠B = 30°∴AD = 1/2 AB= 4∴BD = √（AB? - AD?） =4√3CD = √（AC? - AD?）= 3故：①当∠C为锐角时,BC = BD+CD = 3 + 4√3 ②当∠C为钝角时,BC = BD - CD = 4√3 - 3...