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

Let `alpha, beta` be such that `pi lt alpha - beta lt 3pi ` . If `sin alpha + sin beta = -(21)/( 65)` and `cos alpha + cos beta = - ( 27)/( 65)` then the value of `cos "" ( alpha - beta)/( 2)` is

A

`(-6)/(65)`

B

`(3)/(sqrt130)`

C

`(6)/(65)`

D

`- (3)/(sqrt130)`

Text Solution

Verified by Experts

The correct Answer is:
D
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