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Prove that cosalpha+cosbeta+cosgamma+cos...

Prove that `cosalpha+cosbeta+cosgamma+cos(alpha+beta+gamma)`= `4cos((alpha+beta)/2)cos((beta+gamma)/2)cos((gamma+beta)/2)`

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PATHFINDER-TRIGONOMETRIC RATIOS AND IDENTITIES-QUESTION BANK
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  2. If (sin(theta+alpha))/(cos(theta-alpha))=(1-m)/(1+m) prove that tan((p...

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  3. Prove that cosalpha+cosbeta+cosgamma+cos(alpha+beta+gamma)= 4cos((alph...

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  5. show that (sinx)/(cos3x)+(sin3x)/(cos9x)+(sin9x)/(cos27x)=1/2(tan27x-t...

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  6. If in a triangle ABC cot(A/2)+cot(C/2)=2cot(B/2) then find the minimum...

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  7. If in triangle ABC cosA+cosB+cosC=3/2 then prove that triangle is equi...

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  8. If tan(alpha/2)=sqrt((a-b)/(a+b)) tan(beta/2) prove that cosalpha=(aco...

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  9. If tanalpha=1/7 ,sinbeta=1/sqrt10 prove that alpha+2beta=(pi/4) where ...

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  10. Show that 2^(sinx)+2^(cosx)ge2^(1-(1/sqrt2))

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  11. (sin(-660^@)tan(1050^@).sec(420^@))/(cos(225^@)cosec(315^@)cos(510^@))...

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  14. The expression 3{sin^4((3pi/2)-alpha)+sin^4(3pi-alpha)} -2{sin^6(pi/2+...

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  15. cos 510^@cos330^@+sin 390^@cos120^@=

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  16. If ABCD is a cyclic quadrilateral then the value of cosA+cosB+cos C+co...

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  17. If (secA-tan A)(secB -tan B)(sec C-tan C)(sec A+tan A)(sec B+tan B)(se...

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  18. The value of the expression 1-sin^2y/(1+cosy)+(1+cosy)/siny-siny/(1-co...

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  19. sin^2A+sin^2(A-B)+2sinAcosBsin(B-A) is equal to

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  20. Let A and B denote the statements A:cos alpha+cos beta+cos gamma=0,B:s...

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