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If A+B+C=(3pi)/2, t h e ncos2A+cos2B+cos...

If `A+B+C=(3pi)/2, t h e ncos2A+cos2B+cos2C` is equal to `1-4cos Acos BcosC` `4sinAsinBsinC` `1+2cosAcosBcosC` `1-4sinAsinBsinC`

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If A+B+C=(3pi)/2, t h e ncos2A+cos2B+cos2C is equal to (a) 1-4cos Acos BcosC (b) 4sinAsinBsinC (c) 1+2cosAcosBcosC (d) 1-4sinAsinBsinC

If A+B+C =(3pi)/(2) , then cos2A+cos2B+cos2C is equal to-

If A+B+C = pi , prove that : cos2A +cos2B +cos2C =-1-4cosAcosBcosC .

If A+B+C=(3pi)/(2) , then show that cos 2A+cos 2B+cos 2C=1-4 sin A sin B sin C .

If A+B+C=pi , prove that : cos2A+cos2B+cos2C=-1-4cosA cosB cosC

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If A+B=C, then cos^(2)A+cos^(2)B+cos^(2)C-2cosAcosBcosC=

if A+ B + C = pi, and cos A = cos B cos C, show that 2 cot B cot C=1.

In DeltaABC , prove that: cos2A+cos2B-cos2C=1-4sinAsinBcosC

ALLEN-TRIGONOMETRIC RATIOS AND IDENTITIES-All Questions
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  2. In any triangle A B C ,\ sin A-cos B=cos C ,\ the angle\ B is a.pi...

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  3. If A+B+C=(3pi)/2, t h e ncos2A+cos2B+cos2C is equal to 1-4cos Acos Bc...

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  4. Prove that 5 cos theta+3cos(theta+(pi)/(3))+3 lies between -4 and 10.

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  7. sum(r=1)^(n-1)cos^(2) (rpi)/2 is equal to

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  9. Prove that tan alpha+2 tan 2 alpha+2^(2)tan2^(2)alpha+.................

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  10. S=cosecx+cosec 2x+cosec 4x+…+cosec 2nx=cot(x/2)−cot2nx

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  14. The two legs of a right triangle are sin theta+sin((3pi)/(2)-theta) an...

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  15. If tantheta=sqrt(a/b)where a , b are positive reals then the value o...

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  16. The expression (sin(alpha+theta)-"sin"(alpha-theta))/(cos(beta-theta)-...

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  17. Exact value of cos 20^0+2sin^2\ \ 55^0-sqrt(2)sin65^0\ is- a.1 b. 1/(...

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  18. If cos(theta+phi)=mcos(theta-phi) ,then tantheta is equal to a.((1+m)...

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