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cos2 theta+2 costheta is always...

`cos2 theta+2 costheta` is always

A

greater than `- 3//2`

B

less than or equal to `3//2`

C

greater than or equal to `- 3//2`

D

none of these

Text Solution

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The correct Answer is:
C
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ML KHANNA-TRIGONOMETRY RATIOS AND IDENTITIES-PROBLEM SET (2) ( MULTIPLE CHOICE QUESTIONS)
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  2. sqrt( 3) sin x + cos x is maximum when x is

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  3. The set of values of 'a' for which the equation sqrt(a) "cos" x -2 "...

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  4. Given 12 sin theta + 5 cos theta =2 x^(2) - 8 x +21 and theta and x a...

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  5. If cos 25^(@) + sin 25^(@) =0, then: cos 50^(@)=

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  6. The equation sin x ( sin x + cos x ) = k has real solution if and only...

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  7. The maximum value of 12 sin theta -9 sin ^(2) theta is

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  8. cos2 theta+2 costheta is always

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  9. If l,g are the least and greatest values of 9 cos 2theta - 24 cos thet...

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  10. The ratio of the greatest value of 2-cos x+s in^2x to its least value ...

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  11. If cos A = 3/4 then the value of 32sin( A/2)* sin (5A/2) is.

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  12. The value of sin^3 10^0+sin^3 50^0-sin^3 70^0 is equal to -3/2 (b) 3/...

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  13. If y = 4sin ^(2) theta - cos 2 theta, then y lies in the interval

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  14. If x = ( 4 lambda)/( 1+ lambda^(2)) and y = ( 2 - 2 lambda^(2))/( 1+ ...

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  15. The equation sin^2theta=(x^2+y^2)/(2x y),x , y!=0 is possible if

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  16. The given expression sec^2 theta =(4xy)/((x+y)^(2)) is true if and onl...

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  17. If sin x + sin y = 3 ( cos y - cos x ), then the value of sin 3x + si...

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  18. If A+B+C= pi ( A,B,C gt 0) and the angle C is obtuse, then

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  19. If sin(x+3 alpha)=3sin (alpha-x) then

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  20. If 0 lt x lt 1", then " sqrt(1+x^(2))[{x cos (cot^(-1)x) + sin ( cot...

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