有没有会的大神，求具体解答过程！

consider △ADC

AD/sin60° = CD/sin(180°-60°-54°)

AD/sin60° = CD/sin66°                    (1)

consider △ABD

AB/sin(180°-54°) = AD/sin∠B           

AB/sin126° = AD/sin∠B           

AB/sin54° = AD/sin∠B                      (2)

cosider △ABC

AC/sin∠B = AB/sin60°                      (3)

AB=AC+CD                                       (4)

from (3) and (4)

AB=AC+CD

AB= AB(sin∠B/sin60°)+CD               (5)

from (2) and (5)

AB= AB(sin∠B/sin60°)+CD

AD(sin54°/sin∠B)= AD(sin54°/sin∠B)(sin∠B/sin60°)+CD

AD(sin54°/sin∠B)= AD(sin54°/sin60°)+CD                   (6)

from (1) and (6)

AD(sin54°/sin∠B)= AD(sin54°/sin60°)+CD

 CD(sin60°/sin66°)(sin54°/sin∠B)=  CD(sin60°/sin66°)(sin54°/sin60°)+CD

(sin60°.sin54°)/(sin66°.sin∠B)=  (sin54°/sin66°)+1

sin∠B =(sin60°.sin54°).[(sin54°/sin66°)+1]/sin66°