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If A+B+C=3pi/2. Then cos 2A +cos 2B+cos2...

If `A+B+C=3pi/2`. Then `cos 2A +cos 2B+cos2C` is equal to

A

`1-4 cos A cos B cos C`

B

`4 sin A sin B sin C`

C

`1+2 cos A cos B cos C`

D

`1-4 sin A sin B sin C`

Text Solution

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The correct Answer is:
D
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TARGET PUBLICATION-FACTORIZATION FORMULAE-CRITICAL THINKING
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  2. Prove that tan 20^(@) tan 40^(@) tan 80^(@)=tan 60^(@)

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  3. The value of (tan 70^(@) - tan 20^(@))/( tan 50^(@))=

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  4. The value of tan20^(@)+2 tan50^(@)-tan70^(@), is

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  5. cosec 48^(@) + cosec 96^(@) + cosec 192^(@) + cosec 384^(@)=

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  6. If the value of cos((2pi)/7) + cos((4pi)/7)+cos((6pi)/7)+cos((7pi/7))=...

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  7. The expression cos^(2)(A-B)+cos^(2)B-2cos(A-B)cosAcosB is

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  8. If A=tan6^(@) tan 42^(@) and B= cot 66^(@)cot 78^(@) then-

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  9. If A, B, C are the angles of a triangle, then sin 2A + sin 2B - sin 2C...

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  10. If A+B+C=pi , prove that cos 2A +cos 2B +cos 2C=-1-4cos A cos Bcos ...

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  11. If x +y+z = 180^@, then cos2x + cos2y-cos2z is equal to

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  12. If A+B+C=3pi/2. Then cos 2A +cos 2B+cos2C is equal to

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  13. if A+B+C=pi then cosA/(sinBsinC)+cosB/(sinCsinA)+cosC/(sinAsinB)=

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  14. If A, B, C are the angles of a triangle then sin^(2)A+sin^(2)B+sin^(2)...

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  15. Prove that: cos^2A+cos^2(A+pi/3)+cos^2(A-pi/3)=3/2

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

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  17. In a triangle ABC, the value of sinA+sinB+sinC is

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  18. If A+B+C = 180^@ then (sin 2A + sin 2B + sin 2C) / (cosA + cosB + cosC...

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  19. If alpha+beta+gamma=2pi then

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  20. In a DeltaABC sum((cotA+cotB)/(tanA+tanB)) is equal to

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