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In DeltaABC, a=9, b=8 and c=4, then 3cos...

In `DeltaABC, a=9, b=8` and c=4, then `3cosB-6cosC=?`

A

4

B

`-4`

C

3

D

`-3`

Text Solution

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The correct Answer is:
B
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NAGEEN PRAKASHAN-TRIGNOMETRIC FUNCTIONS-EXERCISES 3P
  1. If 4sin^(2)theta=3, then general value of theta is:

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  2. If sin7theta=cos5 theta, then general value of theta is:

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  3. If tan3theta=cottheta, then general value of theta is :

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  4. Find the general value of theta from the equation tantheta+tan2theta+t...

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  5. The solution of tantheta+cottheta=2 is:

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  6. The solution of cos2theta=cos^(2)theta is:

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  7. cottheta=-sqrt(3) and cosec theta=2

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  8. Solve: 2sin^(2)theta+sin^(2)2theta=2

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  9. If sqrt(3)sintheta-costheta=0, then one general value of theta is:

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  10. In DeltaABC, a=12 m, angleB=30^(@) and angleC=90^(@), then area of Del...

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  11. In DeltaABC, a=12 cm, angleB=30^(@) and angleC=90^(@), then area of De...

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  12. In DeltaABC, cotA/2, cotB/2, cotC/2 are in A.P., then the true stateme...

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  13. If a, b, c are in A.P then cot(A/2),cot(B/2),cot(C/2) are in

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  14. In DeltaABC, a=9, b=8 and c=4, then 3cosB-6cosC=?

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  15. In DeltaABC, If 1/(a+b)+1/(b+c)=3/(a+b+c), then angleB=?

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  16. Prove that in triangleABC, a^3cos(B-C)+b^3cos(C-A)+c^3cos(A-B)=3abc

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  17. In DeltaABC, (b+c)/(11) = (c+a)/(12)=(a+b)/(13), prove that: cosA:co...

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  18. In DeltaABC, (b-c)cot(A/2)+(c-a)cot(B/2)+(a-b)cot(C/2)=?

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  19. In DeltaABC, if (2cosA)/(a)+(cosB)/(b)+(2cosC)/(2)=a/(bc)+b/(ca), then...

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  20. In DeltaABC, a=3,b=4,c=2, then cosA/2=?

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