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Prove that: cos Acos(60^0-A)cos(60^0+A)=...

Prove that: `cos Acos(60^0-A)cos(60^0+A)=1/4cos3A`

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RD SHARMA ENGLISH-TRANSFORMATION FORMULAE-All Questions
  1. 2cos(pi/13)cos(9pi/13)+cos(3pi/13)+cos(5pi/13)=0

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  2. Prove that: sin10^0sin30^0sin50^0sin70^0=1/(16)dot

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  3. Prove that: cos Acos(60^0-A)cos(60^0+A)=1/4cos3A

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  4. Prove that 4sinthetasin(pi/3+theta)sin((2pi)/3+theta)=sin3theta

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  5. Express each of the following as the sum or difference of sines and ...

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  6. Express each of the following as the sum or difference of sines and ...

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  7. Express each of the following as the sum or difference of sines and ...

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  8. Express each of the following as the sum or difference of sines and ...

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  9. Prove that; 2sin((5pi)/12)sin(pi/12)=1/2

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  10. Prove that 2sin((5pi)/12)cos(pi/12)=(2+sqrt3)/2

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  11. Find the value of 2cos((5pi)/12) cos(pi/12) and 2sin((5pi)/12)cos(pi/1...

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  12. Show that: sin 50^0cos85^0=(1-sqrt(2)sin35^0)/(2sqrt(2))

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  13. sin25^@cos115^@=1/2(sin40^@-1)

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  14. Prove that: 4\ costhetacos\ (pi/3+theta)cos(pi/3-theta)=cos3theta

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  15. Prove that: cos 10^0cos30^0cos 50^0cos 70^0=3/(16)

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  16. Prove that: sin20^0sin40^0sin80^0=(sqrt(3))/8

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  17. Prove that: t a n 20^0tan40^0tan60^0tan80^0=3

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  18. Prove that: \ sin 10^0sin 50^0sin 60^0sin 70^0=(sqrt(3))/(16)

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  19. Prove that: cos40^0cos80^0cos 160^0=\ -1/8

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  20. Prove that: \ cos 20^0cos 40^0cos 80^0=1/8

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