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Cos (-(9pi)/(4))=...

`Cos (-(9pi)/(4))=`

A

0

B

-1

C

`-(1)/(sqrt(2))`

D

`(1)/(sqrt(2))`

Text Solution

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AAKASH SERIES-TRIGONOMERTIC RATIOS-EXERCISE - I
  1. Sin 4530^(@)=

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  2. Cos (-(9pi)/(4))=

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  3. sin 120^(@) cos 150^(@)- cos 240^(@) sin 330^(@) =

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  4. If tan 35^(@) = k , then the value of ( tan 145^(@) - tan 125^(@))/...

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  5. If sin A = 3/5, tan B = 1/2 and pi/2 lt A lt pi and pi lt B lt (3pi)/...

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  6. If theta lies in the first quadrant and 5 tan theta = 4 , " then "...

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  7. If Sin^(2) theta = K^(2) ( 0 lt k lt 1) and 180^(@) lt theta lt 270^(@...

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  8. If tan theta = 3/4 and theta is not in the first quadrant then (sin (p...

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  9. If tan theta = p/q then (p sin theta - q cos theta)/(p sin theta + q c...

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  10. a sin^(2) theta + b cos^(2) theta =c implies tan^(2) theta =

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  11. If tan theta = -4//3 " then " sin theta =

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  12. If Tan theta = (2 x(x+1))/(2x+1) then Sin theta =

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  13. If tan theta =(1)/(sqrt(7)) and theta is an acute angle , then ("cos...

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  14. If alpha and beta are complementary angles then sin^(2)(90^(@)-alpha)+...

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  15. cos^(2) 9^(@)+cos^(2)18^(@)+cos^(2) 27^(@)+...+cos^(2)81^(@)=

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  16. sum(k=1)^3 cos^(2)((2k-1)(pi)/(12))=

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  17. tan1^(@).tan2^(@).tan3^(@)...tan89^(@)=

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  18. log10 tan1^@+log10 tan2^@+log10 tan3^@+......+log10 tan89^@=..........

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  19. cot. (pi)/(20) cot. (3pi)/(20) cot. (5pi)/(20) cot. (7pi)/(20) cot. (9...

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  20. Sin24^(@)+sin32^(@)+sin204^(@)+sin212^(@)=

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