According to the sine theorem, the AC ratio sinB is equal to 2, AB is equal to 2 sinc and BC is equal to 2sinA, so AB+2 BC = 2 SINC+4 SINA = 2 SIN (180-b-a)+4 SINA = 2 SIN (b+a)+4 SINA. Then, the angle B=60 degrees is substituted into the above formula, and the trigonometric function about the angle a is converted. Typing is difficult, I hope it will help you. As for the specific answer, just do the math yourself.