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Prove that cos 10^(@) cos20^(@) + sin ...

Prove that
`cos 10^(@) cos20^(@) + sin 45^(@) cos145^(@) + sin 55^(@) cos245^(@) = 0`

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Prove that sin 80^(@) cos20^(@) + sin45^(@) cos145^(@)+sin 55^(@) cos245^(@) = 0

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Prove that cos 10^(@) + cos 110^(@) + cos 130^(@) = 0

Prove that cos20^(@) cos40^(@) cos80^(@) = 1/8

Prove that cos32^(@) sin20^(@) + cos144^(@) cos2^(@) + sin68^(@) cos56^(@) = 0

Prove that cos 60^(@)=cos^(2)30^(@)-sin^(2)30^(@) .

Prove that 1 + (cos105^(@) + cos 165^(@))/(sin 105^(@) + sin 375^(@))= 0

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CHHAYA PUBLICATION-TRANSFORMATIONS OF SUMS AND PRODUCTS-Short Answer Type Questions
  1. Prove that cos32^(@) sin20^(@) + cos144^(@) cos2^(@) + sin68^(@) cos...

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  2. Prove that cos306^(@) + cos234^(@) + cos162^(@) + cos18^(@) = 0

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  3. Prove that cos 10^(@) cos20^(@) + sin 45^(@) cos145^(@) + sin 55^(@)...

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  4. Prove that cos24^(@) + cos 55^(@) + cos125^(@) +cos204^(@) + cos300^...

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  5. Prove that cos20^(@) cos40^(@) cos80^(@) = 1/8

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  6. Prove that 8 sin20^(@) sin40^(@) sin80^(@) = sqrt3

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  7. Prove that tan20^(@) tan40^(@) tan80^(@) = sqrt3

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  8. Prove that cos40^(@) cos80^(@) cos160^(@) = -1/8

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  9. Prove that cos thetacos(60^(@)- theta)cos(60^(@)+theta) = 1/4 cos 3 ...

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  10. Prove that 4 sin theta sin(pi/3 + theta) sin (pi/3-theta) = sin 3 th...

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  11. Prove that cos alpha cos (120^(@) + alpha) cos (240^(@) + alpha) = 1...

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  12. Find the value: sin 78^(@) - sin18^(@) + sin 30^(@) - sin42^(@)

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  13. Find the value: sec20^(@) sec40^(@) sec80^(@)

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  14. Find the value: sqrt3 cot20^(@) cot40^(@)cot80^(@)

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  15. Find the value: 1/(2sin 10^(@))-2 sin 70^(@)

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  16. Prove the following identities : 4 sin 23^(@) sin37^(@) sin 83^(@) =...

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  17. Prove the following identities : cos2 A + cos 4A + cos 6A + cos8A =4...

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  18. Prove the following identities : (sin(A+B) - 2 sin A + sin (A-B))/(c...

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  19. Prove the following identities : (sin theta +sin 3 theta + sin 5 the...

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  20. If 13theta =pi " show that"cos 3 theta + cos 5 theta + 2 cos theta co...

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