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The least vlaue of (1)/(5cosx+12sinx+15)...

The least vlaue of `(1)/(5cosx+12sinx+15),` is

A

`-18`

B

`1//28`

C

28

D

`1//18`

Text Solution

Verified by Experts

The correct Answer is:
B
We have, `-13le 5cosx+12sin x le13 "for all"x inR`
`implies2le5 cosx+12 sinx+15le 28"for all"x inR`
`implies1/28le(1)/(5cosx+12sinx+15)is 1/28`
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OBJECTIVE RD SHARMA-TRIGONOMETRIC RATIOS AND IDENTITIES-Chapter Test
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  10. If cosectheta=(p+q)/(p-q),then cot(pi,//4+theta//2)=

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  11. If sinalpha+sin beta=a and cos alpha+cos beta=b,then sin(alpha+beta)=

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  12. If cos(alpha+beta)=4/5, sin(alpha-beta)=5/13and alpha, beta between 0 ...

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  14. The value of sum(k=1)^(3) cos^(2)(2k-1)(pi)/(12), is

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  15. If (a^(2)+1)/(2a)=costheta, then (a^(6)+1)/(2a^(3))=

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  16. The value of (1)/(cos290^(@))+(1)/(sqrt3sin250^(@)) is equal to

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  17. If tan alpha=(1+2^(-x))^(-1), tan beta=(1+2^(x+1))^(-1) then alpha+bet...

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  18. A and B are positive acute angles satisfying the equations 3cos^(2)A...

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