If x = cos α + i sin α and y = cos β + i sin β, then the value of \(\frac{{x - y}}{{x + y}}\) is:

\(i\tan \left( {\alpha - \beta } \right)\)

\(\tan \left( {\frac{\alpha }{\beta }} \right)\)

\(\tan \left( {\frac{{\alpha - \beta }}{2}} \right)\)

\(i\tan \left( {\frac{{\alpha - \beta }}{2}} \right)\)

If x = cos α + i sin α and y = cos β + i sin β, then the value

1.	If x = cos α + i sin α and y = cos β + i sin β, then the value of \(\frac{{x - y}}{{x + y}}\) is:
A.	\(\tan \left( {\frac{\alpha }{\beta }} \right)\)
B.	\(\tan \left( {\frac{{\alpha - \beta }}{2}} \right)\)
C.	\(i\tan \left( {\frac{{\alpha - \beta }}{2}} \right)\)
D.	\(i\tan \left( {\alpha - \beta } \right)\)
Answer» D. \(i\tan \left( {\alpha - \beta } \right)\)