If a = cos α + i sin α, b = cos β + i sin β, c = cos γ + i sin γ and \(\frac {b}{c} + \frac {c}{a} + \frac {a}{b} = 1\) then [cos (β - γ) + cos (γ - α) + cos (α - β)] is equal to:

If a = cos α + i sin α, b = cos β + i sin β, c = cos γ + i s

1.	If a = cos α + i sin α, b = cos β + i sin β, c = cos γ + i sin γ and \(\frac {b}{c} + \frac {c}{a} + \frac {a}{b} = 1\) then [cos (β - γ) + cos (γ - α) + cos (α - β)] is equal to:
A.	3 / 2
B.	-3 / 2
C.	0
D.	1
Answer» E.