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Let alpha, beta be such that pi lt=alpha...

Let `alpha, beta` be such that `pi lt=alpha lt=beta lt=3pi`if `sinalpha + sinbeta = -21/65` and `cosalpha + cosbeta = -27/65`, then the value of `cos""(alpha - beta)/65` is :

A

`-3/sqrt(130)`

B

`3/sqrt(130)`

C

`6/65`

D

`-6/65.`

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The correct Answer is:
A
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