Hello from MrBillDoesMath!
Answer:
BC = 3 * sin (66)/ sin(38)
Discussion:
From the law of sines:
sin(38) /3 = sin(66)/ BC
BC * ( sin(38)/3 ) = sin(66) => multiply both sides by BC
BC = sin(66) / ( sin(38)/3) => multiply both sides by ( 3/sin(38) )
BC = 3 * sin (66)/ sin(38)
which is the first choice.
Regards,
MrB
P.S. I'll be on vacation from Friday, Dec 22 to Jan 2, 2019. Have a Great New Year!