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Prove that in triangle A B C ,cos^2A+cos...

Prove that in triangle `A B C ,cos^2A+cos^2B-cos^2C=1-2sinAsinBcosCdot`

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CENGAGE PUBLICATION-TRIGONOMETRIC FUNCTIONS-All Questions
  1. Prove that 2sin2^0+4sin4^0+6"sin"6^0+.......+180sin180^0=90cot1^0dot

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  2. If A+B+C=180^@, then prove thatcos2A + cos2B +cos2C=-1-4cosA cosB cosC...

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  3. Prove that in triangle A B C ,cos^2A+cos^2B-cos^2C=1-2sinAsinBcosCdot

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  4. In triangle ABC, prove that sin(B+C-A)+sin(C+A-B)+sin(A+B-C) =4sin A...

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  5. Prove that sum(k=1)^(n-1)(n-k)cos(2kpi)/n=-n/2, wherengeq3 is an int...

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  6. If (tan(ln6)dottan(ln2)dot"tan"(ln3))/(tan(ln6)-tan(ln2)-"tan"(ln3))=k...

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  7. In any triangle A B C ,sin^2A-sin^2B+sin^2C is always equal to (A) 2s...

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  8. If cot^2Acot^2B=3, then the value of (2-cos2A)(2-cos2B) is

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  9. If tanalpha=m/(m+1) and tanbeta=1/(2m+1) . Find the possible values o...

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  10. If u=sqrt(a^2 cos^2 theta + b^2sin^2theta)+sqrt(a^2 sin^2 theta + b^2 ...

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  11. The value of sin^2 12^0+sin^2 21^0+sin^2 39^0+sin^2 48^0-sin^2 9^0-sin...

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  12. The value of f(x)=x^4+4x^3+2x^2-4x+7, when x=cot((11pi)/8) is

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  13. Prove that sqrt3 "cosec" 20^@-sec20^@=4

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  14. If (1+sint)(1+cost)=5/4 then find the value of (1-sint)(1-cost)dot

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  15. If alpha,beta,gamma,delta are the smallest positive angles in ascendi...

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  16. (sin^2A-sin^2B)/(sinAcosA-sinBcosB)is equal to

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  17. If cos25^0+sin25^0=p , then cos50^0 is

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  18. The value of cot((7pi)/16)+2cot((3pi)/8)+cot((15pi)/16) is (a)4 (b...

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  19. If t a n^2theta=2t a n^2varphi+1 , prove that cos2theta+sin^2phi =0.

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  20. If tanA.tanB=1/2,t h e n(5-3cos2A)(5-3cos2B)= (a)2 (b) 8 (c) 12 ...

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