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If sinalpha+sinbeta=a ,cosalpha+cosbeta=...

If `sinalpha+sinbeta=a ,cosalpha+cosbeta=b=>sin(alpha+beta)`=

A

ab

B

`a+b`

C

`(2ab)/(a^(2)-b^(2))`

D

`(2ab)/(a^(2)+b^(2))`

Text Solution

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The correct Answer is:
D
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OBJECTIVE RD SHARMA ENGLISH-TRIGONOMETRIC RATIOS AND IDENTITIES-Chapter Test
  1. alpha and beta are acute angles and cos2alpha = (3cos2beta-1)/(3-cos2b...

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  2. If cosectheta=(p+q)/(p-q), then cot(pi/4+theta/2)=

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  3. If sinalpha+sinbeta=a ,cosalpha+cosbeta=b=>sin(alpha+beta)=

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  4. If cos(alpha+beta)=(4)/(5) and sin(alpha-beta)=(5)/(13) , where alpha ...

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  5. about to only mathematics

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  6. The value of sum(k=1)^(3) cos^(2)(2k-1)(pi)/(12), is

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  7. If (a^(2)+1)/(2a)=costheta, then (a^(6)+1)/(2a^(3))=

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  8. The greatest integer less than or equal to (1)/(cos 290^(@))+(1)/(sqrt...

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  9. If tan alpha=(1+2^(-x))^(-1), tan beta=(1+2^(x+1))^(-1) then alpha+bet...

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  10. A and B are positive acute angles satisfying the equations 3cos^(2)A...

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  11. If T(n)=cos^(n)theta+sin ^(n)theta, then 2T(6)-3T(4)+1=

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  12. The maximum value of 1+8sin^(2)x^(2)cos^(2)x^(2) is

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  13. about to only mathematics

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  14. The expression 3{sin^(6)""((pi)/(2)+alpha)+sin^(6)(5pi-alpha)} is equa...

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  15. The minimum value of (1)/(3sintheta-4costheta+7), is

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  16. The maximum value of cos^(2)A+cos^(2)B-cos^(2)C, is

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  17. If ys invarphi=x s in(gamma+delta)=cos(alpha-beta)sin(gamma-delta), pr...

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  18. cosx{(cosx)/(1-sinx)+(1-sinx)/(cosx)}, is

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  19. If tanx=(b)/(a), then find the value of sqrt((a+b)/( a-b ))+sqrt((a-b)...

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  20. In tantheta+sec theta=sqrt3,0ltthetaltpi, then theta is equal to

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