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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

`-7/9`

B

`-3/5`

C

`1/3`

D

`2/9`

Text Solution

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Knowledge Check

  • 5(tan^(2)x-cos^(2)x) = 2cos2x +9 , then the value of cos4x is:

    A
    `-3//5`
    B
    `1//3`
    C
    `2//9`
    D
    `-7//9`

  • If sin (x+y)=cos (x-y), then the value of cos^2x is :

    A
    3
    B
    5
    C
    `1/4`
    D
    `1/2`

  • If (sin x + cos x)/(sin x - cos x) = (6)/(5) , then the value of (tan^(2) x + 1)/(tan^(2) x-1) is :

    A
    `(35)/(61)`
    B
    `(61)/(60)`
    C
    `(60)/(61)`
    D
    `(61)/(35)`

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