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If cosalpha+cosbeta=0=sinalpha+sinbeta,c...

If `cosalpha+cosbeta=0=sinalpha+sinbeta,cos2alpha+cos2beta` is equal to a)`-2sin(alpha+beta)` b)`2cos(alpha+beta)` c)`2sin(alpha-beta)` d)`-2cos(alpha+beta)`

A

`-2sin(alpha+beta)`

B

`2cos(alpha+beta)`

C

`2sin(alpha-beta)`

D

`-2cos(alpha+beta)

Text Solution

Verified by Experts

The correct Answer is:
D
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