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If cos A = sqrt((sqrt(2)+1)/(2sqrt(2))),...

If `cos A = sqrt((sqrt(2)+1)/(2sqrt(2)))`, find the value of `cos2A`

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The correct Answer is:
`1/sqrt(2)`
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VIKRAM PUBLICATION ( ANDHRA PUBLICATION)-TRIGONOMETRIC RATIOS UPTO TRANSFORMATIONS-EXERCISE - 6(F)
  1. If cos A = sqrt((sqrt(2)+1)/(2sqrt(2))), find the value of cos2A

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  2. If A+B+C=pi then prove that sin2A-sin2B+sin2C=4cosAsinBcosC

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  3. If A, B, C are angles of a triangle , prove that cos 2A - cos 2B + ...

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  4. If A, B, C are angles in a triangle , prove that sin A+ sin B -sin ...

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  5. IF A,B,C are angles in the triangle, then prove that cosA+cosB-cosC=...

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  6. If A, B , C are angles in a triangle, then the sin ^(2)A+sin ^(2)B - s...

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  7. If A, B, C are angles in a triangle , then prove thatcos^(2)A+cos^(2...

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  8. If A+B+ C =pi, then prove that cos ^(2) (A/2)+ cos ^(2) (B/2) +cos ^(2...

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  9. If A, B , C =pi, then prove that cos ^(2). (A)/(2)+ cos^(2). (C)/(2)...

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  10. In triangle ABC, prove that cos .(A)/(2)+cos.(B)/(2)+cos. (C)/(2) =4 c...

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  11. In Delta ABC, prove that cos. (A)/(2)+cos. (B)/(2) - cos .(C)/(2)=4cos...

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  12. In triangle ABC , prove that sin .(A)/(2)+ sin. (B)/(2) -sin. (C)/(2)=...

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  13. If A+B+C=(pi)/(2), then prove that cos 2A + cos 2B + cos 2C=1+4 sin A ...

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  14. If A+B+C=(3pi)/(2), prove that cos ^(2)A+ cos ^(2) B- cos ^(2)C=-2 cos...

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  15. If A+B+C=270^(@) then show that sin2A+sin2B-sin2C=-4sinAsinBcosC

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  16. If A+B+C=270^(@) then show that sin2A+sin2B-sin2C=-4sinAsinBcosC

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  17. If A+B+C=0^(@) then prove that sinA+sinB-sinC=-4"cos"A/2"cos"B/2"sin...

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  18. If A+B+C+D=360^(@) then show that sinA-B+sinC-sinD= -4cos((A+B)/2)...

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  19. If A+B+C+D=360^(@), the prove that cos 2A + cos 2B + cos 2C + cos 2D =...

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  20. If A+B+C = 2S, then prove that sin(S-A)+sin(S-B)+sinC = 4 cos ((S-A)...

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  21. IF A+B+C=2S, then prove that cos(S-A)+cos(S-B)+cosC=-1+4cos""(S-A)/2...

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