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If a=b cos((2pi)/3)= c cos((4pi)/3), the...

If `a=b cos((2pi)/3)= c cos((4pi)/3),` then write the value of `a b+b c+c a`

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RD SHARMA ENGLISH-TRIGONOMETRIC RATIOS OF COMPOUND ANGLES-All Questions
  1. If tan(A+B)=p\ a n dtan(A-B)=q then write the value of tan2Bdot

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  2. If ("cos"(x-y))/("cos"(x+y))=m/n , then write the value of t a n x\ t ...

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  3. If a=b cos((2pi)/3)= c cos((4pi)/3), then write the value of a b+b c+c...

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  4. If A+B=C , then write the value of t a n A\ t a n B\ t a n Cdot

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  5. If sinalpha-sinbeta=a and cosalpha+cosbeta=b then write the value of "...

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  6. The value of sin^2 75^0-sin^2 15^0 is a. 1//2 b. sqrt(3)//2 c. 1 d. 0

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  7. If A+B+C=180^0,\ then s e c A(cos B cos C-sin B sin C) is equal to:

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  8. tan20^@+tan40^@+sqrt3 tan20^@ tan40^@= (a).sqrt3/4 (b).sqrt3/2 (c).s...

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  9. If tanA=a/(a+1) and tanB=1/(2a+1) then the value of A+B is: (a).0...

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  10. If 3sintheta+4costheta =5 then find the value of: 4sintheta-3costheta

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  11. The value of: tan3A-tan2A-tanA =

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  12. If A+B+C=180^0 , then (t a n A+t a n B+t a n C)/(t a n A\ t a n B\ t a...

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  13. If cosP=1/7a n d\ cos Q=(13)/(14)w h e r e\ P\ a n d\ Q both are acute...

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  14. If cot(alpha+beta)=0\ t h e n\ "sin"(alpha+2beta) is equal to a. sin...

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  15. (cos 10^0+sin 10^0)/(cos 10^0-sin 10^0) is equal to tan55^0 b. cos ...

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  16. The value of cos^2(pi/6+theta)-sin^2\ \ (pi/6-theta) is a,1/2cos2theta...

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  17. If t a ntheta1t a ntheta2=k , then ("cos"(theta1-theta2))/("cos"(theta...

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  18. If A-B=pi//4 , then (1+t a n A)(1-t a n B) is equal to 2 b. 1 c. 0 d. ...

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  19. The maximum value of sin^2(120^0+theta)+sin^2(120^0-theta) is a.1//2 b...

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  20. If cos(A-B)=3/5 and tanA tanB=2, then a.cos A cosB=1/5 b. co...

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