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If 5(tan^2x - cos^2x)=2cos 2x + 9, then ...

If `5(tan^2x - cos^2x)=2cos 2x + 9`, then the value of cos4x is

A

`(2)/(9)`

B

`-(7)/(9)`

C

`-(3)/(5)`

D

`-(1)/(3)`

Text Solution

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The correct Answer is:
B
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