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If x=y cos((2pi)/(3))=z cos ((4pi)/(3)) ...

If `x=y cos((2pi)/(3))=z cos ((4pi)/(3))` then `xy+yz+zx=`

A

0

B

1

C

-1

D

`1/2`

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AAKASH SERIES-TRIGONOMERTIC RATIOS-EXERCISE- II
  1. If x=Sin 1, y = Sin 2, z= Sin 3 then

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  2. Which of the following is correct ?

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  3. If x=y cos((2pi)/(3))=z cos ((4pi)/(3)) then xy+yz+zx=

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  4. If A,B,C are qcute angles such that sin(B+C-A)=cos(C+A-B)=tan(A+B-C)=1...

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  5. In Delta le ABC, 5 cos A + 3 = 0 then the quadratic equation whose roo...

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  6. If sin A , cos A and tan A are in G.P. then cot^(6) A- cot^(2) A =

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  7. sin^(2) theta = ((x+y)^(2))/(4xy) is true if and only if

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  8. Which of the following is possible?

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  9. If y=cos^(2) theta + sec^(2) theta , theta != n pi, n in Z then

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  10. If tan 35^(@) +cot 37^(@) +tan 325^(@)=x tan 53^(@)+ tan 127^(@) then ...

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  11. sin^(2) 5^(@)+sin^(2) 10^(@) +sin^(2)15^(@)+...+sin^(2) 180^(@)=

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  12. If K is a positive integer then sin(alpha + pi) + Sin(alpha + 2pi) + S...

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  13. cos theta + cos ( pi + theta ) + cos (2pi + theta) + ...+2n terms =

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  14. sin^(4) theta + 2 sin^(2) theta (1-(1)/("cosec"^(2) theta ) )+ cos^(4)...

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  15. cos^(2) 5^(@) + cos^(2) 10^(@) +cos^(2) 15^(@)+...+cos^(2)360^(@)=

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  16. In Delta ABC, cos""((B+2C+3A)/(2))+ cos""((A-B)/(2))=

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  17. The ratio between (1+cos alpha)/(sin^(2) alpha) and a+((1+cos alpha)/(...

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  18. If theta = (pi)/(21), then (sin23 theta-sin 7 theta)/( sin2 theta + si...

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  19. If 1+sin theta + sin^(2) theta + ...oo= 4+2sqrt(3), 0 lt theta lt pi a...

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  20. If ( sin x + cos x)/(cos^(3)x)=a tan^(3)x+b tan^(2)x+c tan x+d then ...

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