For the equation (1-ix)/(1+ix)=sin.(pi)/...

For the equation `(1-ix)/(1+ix)=sin.(pi)/(7)-i cos.(pi)/(7)`, if `x=tan((kpi)/(28))`, then the value of k can be (where `i^(2)=-1`)

A

1

B

3

C

5

D

9

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The correct Answer is:

C

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