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If a = cos alpha + isin alpha, b = - cos...

If a = cos `alpha + isin alpha, b = - cos beta + isin beta ` then `(ab - (1)/(ab))` is _______

A

`-2i sin (alpha - beta)`

B

`2i sin (alpha - beta)`

C

`2 cos (alpha - beta)`

D

`-2 cos (alpha - beta)`

Text Solution

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The correct Answer is:
A, B
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