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If x=ycos""(2pi)/(3)=zcos""(4pi)/(3), th...

If `x=ycos""(2pi)/(3)=zcos""(4pi)/(3)`, then `xy+yz+zx` is equal to

A

`-1`

B

0

C

1

D

2

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The correct Answer is:
B
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LUCENT PUBLICATION-ADVANCED TRIGONOMETRIC IDENTITIES-EXERCISE 13A
  1. If (-pi)/(2) < theta < (pi)/(2) " and " theta ne pm (pi)/(4), then th...

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  2. If sin theta =3 sin ( theta + 2 alpha), then the value of tan (theta...

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  3. If x=ycos""(2pi)/(3)=zcos""(4pi)/(3), then xy+yz+zx is equal to

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  4. (cos 9^(@) + sin 9^(@))/(cos 9^(@) - sin 9^(@)) equals

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  5. The value of sin 50^(@) - sin 70^(@) + sin 10^(@) is

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  6. Maximum value of 3 cos theta + 4 sin theta is

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  7. If tanalpha=(m)/(m+1)andtan beta=(1)/(2m+1), then (alpha+beta)=?

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  8. (sin(x+y))/(sin(x-y))=(a+b)/(a-b), then (tanx)/(tany)=?

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  9. If tan alpha = (5)/(6) tan beta = (1)/(11) then the value of alpha +...

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  10. Maximum value of sin (x + (pi)/(6)) + cos (x + (pi)/(6)) is

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  11. If cos(alpha+beta)=(4)/(5) and sin(alpha-beta)=(5)/(13) , where alpha ...

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  12. If A = sin^(2)x + cos^(4)x, where x in a real number

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  13. If x = tan 15^(@), y = cosec 75^(@) " and " z =4 sin 18^(@), then

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  14. If sin theta =3 sin ( theta + 2 alpha), then the value of tan (theta...

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  15. Expression (1)/(cos 290^(@)) + (1)/(sqrt(3) sin 250^(@)) equals

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  16. Find the value of:(1+cos""(pi)/(8))(1+cos""(3pi)/(8))(1+cos""(5pi)/(8)...

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  17. Prove that cos^(4)pi/8+cos^(4)(3pi)/(8)+cos^(4)(5pi)/8+cos^(4)(7pi)/...

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  18. cos""(pi)/(15).cos""(2pi)/(15).cos""(4pi)/(15).cos""(8pi)/(15) is equa...

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  19. (2)/(sqrt(2) + sqrt(2) + sqrt(2+2 cos 4x)) equals

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  20. The value of cos 15^(@) cos 7 ((1)/(2))^(@)sin 7 ((1)/(2))^(@) is

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