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5(tan^(2)x-cos^(2)x) = 2cos2x +9 , then ...

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

A

`-7/9`

B

`-3/5`

C

`1/3`

D

`2/9`

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The correct Answer is:
A
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DISHA PUBLICATION-TRIGONOMETRIC FUNCTIONS -EXERCISE-2
  1. 5(tan^(2)x-cos^(2)x) = 2cos2x +9 , then the value of cos4x is:

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  2. The expression (1 + sin 2 alpha )/( cos (2 alpha - 2pi) tan (alpha - (...

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  3. Solve the inequality, cosxle-1/2.

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  4. Two men are on the opposite sides of a tower. They measure the angles ...

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  5. The range of vlaues of the expression 5 cos theta + 3 cos (theta + (pi...

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  6. The value of (1-tan^2 1 5^(@))/(1+tan^2 1 5^(@)) is

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  7. Which pairs of function is identical ?

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  8. If y=(sinx+cos e cx)^2+(cosx+secx)^2 , then the minimum value of y ,AA...

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  9. If tan ((pi)/(4) + theta) + tan ((pi )/(4) - theta) = p sec 2 theta) t...

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  10. Period of sin theta - sqrt2 cos theta is

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  11. tan^(6)20^(@) - 33tan^(2) 20^(@) + 27 tan^(2) 20^(@) + 4=

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  12. Which of the following is correct ?

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  13. if:f(x)=(sinx)/(sqrt(1+tan^2x))-(cosx)/(sqrt(1+cot^2x)), then find the...

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  14. If sin x + sin ^(2) x=1, then the value of cos ^(12) x+3 cos ^(10) x+...

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  15. The value of sin ""(pi)/(16) sin ""(3pi)/(16) sin ""(5pi)/(16) sin ""(...

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  16. General solution of the equation 2 cot ^(2) theta + 2sqrt3 cot theta...

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  17. A man observe that was he has climbed up 1/3 of the length of an incli...

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  18. The number of solutions of tan x+ sec x=2 cos x in (0, 2pi) is

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  19. If sinA=3/5, 0 lt A lt pi/2 and cosB=-12/13, pi lt B lt (3pi)/2, then ...

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  20. The domain of f(x)= sqrt(cos(sinx))+sqrt(logx{x}) where {x} denotes fr...

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  21. The range of f(x) = cos x - sin x is

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