Question

Right triangle abc with right angle at vertex b. angle bac measures 60 degrees. îabc is a right triangle in which ˆ b is a right angle, ab = 1, ac = 2, and bc = v3 . cos c ã— sin a = - - - - - - - - - -
A) -1/4
B) -1/2
C) -1/√3
D) -√3/2