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if a=cos 2 and b =sin7, then...

if `a=cos 2 and b =sin7,` then

A

`a gt0, b gt0`

B

`ab lt0`

C

`a gtb`

D

`a ltb`

Text Solution

Verified by Experts

The correct Answer is:
B
We have, `(pi)/(2)le2^(c)le(3pi)/(4)and 2pilt7^(c)(5pi)/(2)`
`implies2^(c)"is in second quadrant and"7^(c) "is in first quadrnat"`
`impliesa =cos2^(c)lt0and b=sin7^(c)gt0`
`impliesab lt0`
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OBJECTIVE RD SHARMA ENGLISH-TRIGONOMETRIC RATIOS AND IDENTITIES-Section I - Solved Mcqs
  1. if a=cos 2 and b =sin7, then

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  2. The highest value of (1)/(6cosx+8sinx+13), is

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  3. If 0lt thetalt(pi)/(2')and if(y+1)/(1-y)=sqrt((1+sintheta)/(1-sintheta...

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  4. The set of all possible values of alpha in [-pi,pi] such that sqrt((1...

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  5. If |tan A| lt A is acute, then (sqrt((1+sin2A))+sqrt((1-sin2A)))/(sq...

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  6. sec^(2)theta==(4ab)/((a+b)^(2)), where a, b inR is true if and olny if

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  7. Which one is true ?

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  9. Let cos(alpha + beta) = 4//5 and let sin ( alpha - beta)= 5//13, wher...

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  10. If alpha=sin x cos^(3) x and beta=cos x sin^(3) x, then :

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  11. The expression (tan A)/(1-cotA)+(cot A)/(1-tan A) can be written as

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  12. Let P={theta:sintheta-costheta=sqrt2costheta}and Q={theta: sintheta+co...

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  13. If x cos alpha+ y sin alpha= x cos beta + y sin beta=2a(0 lt alpha, be...

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  15. The value of sin^(8)theta+cos^(8)theta+sin^(6)theta cos^(2)theta+3sin^...

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  16. Let F(k)(x)=1/k (sin^(k)x+cos^(k)x), where x in R and k ge 1, then fin...

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  17. If sin(theta+alpha)=a,cos^(2)(theta+beta)=b, then sin(alpha-beta)=

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  18. Q. Let n be an add integer if sin ntheta = sum(r=0)^n(br)sin^rtheta, f...

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  19. Which of the following number(s) is/are rational? sin15^0 (b) cos15^0...

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