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If 5 (tan ^(2) x - cos ^(2) x ) = 2 cos ...

If `5 (tan ^(2) x - cos ^(2) x ) = 2 cos 2x +9`, then the value of `cos 4 x ` is

A

`(-3)/(5)`

B

`(1)/(3)`

C

`(2)/(9)`

D

`-(7)/(9)`

Text Solution

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The correct Answer is:
D
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