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If cos alpha+cos beta=0=sin alpha+sin be...

If `cos alpha+cos beta=0=sin alpha+sin beta`, then `cos 2 alpha+cos 2beta` is equal to

A

`-2 sin (alpha + beta)`

B

`-2 cos (alpha + beta)`

C

`2 sin(alpha +beta)`

D

`2cos(alpha +beta)`

Text Solution

Verified by Experts

The correct Answer is:
B
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