A=60, sin A=

sin C=

sin C=

sin C=

from here, work out cos C

cos C = (I am taking cos C to be positive,

otherwise angle B would come out reflex)

since A+B+C = 180, B=180-(A+C), sin B=sin (A+C)=sin A * cos C + cos A * sin C

=

Now use sine rule in the triangle ABC, you will get b=3c