if (tanalpha-i(sin ""(alpha)/(2)+cos ""(...

if `(tanalpha-i(sin ""(alpha)/(2)+cos ""(alpha)/(2)))/(1+2 i sin ""(alpha)/(2))` is purely imaginary then `alpha` is given by -

A

`npi+(pi)/(4)`

B

`npi-(pi)/(4)`

C

`(2n+1)pi`

D

`2npi+(pi)/(4)`

Verified by Experts

The correct Answer is:

A

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