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Prove that: cos(pi/4+x)+cos(pi/4-x)=sqrt...

Prove that: `cos(pi/4+x)+cos(pi/4-x)=sqrt(2)\ cos x`

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Prove that: cos(pi/4+x)+cos(pi/4-x\ )=sqrt(2)cosx

Prove that cos(pi/4+x)+cos(pi/4-x)=sqrt(2)cosx .

Prove that: cos(pi/4+A)+cos(pi/4-A)=sqrt(2)cosA

Prove that: cos((3pi)/4+x)-cos((3pi)/4-x\ )=sqrt(2)sinx

Prove that: cos((3pi)/4+x)-cos((3pi)/4-x)=-sqrt(2)sinx

Prove that: cos((3pi)/4+x)-cos((3pi)/4-x)=-sqrt(2)sinx

cos((3pi)/(4)+x)-cos((3pi)/(4)-x) = -sqrt(2)sinx

Prove that: cos((3pi)/(4)+A)-cos((3pi)/(4)-A)=-sqrt(2)sinA

Prove that: cos(pi/4-x)cos(pi/4-y)-sin(pi/4-x)sin(pi/4-y)=sin(x+y)

Prove that: cos(pi/7)cos(2pi/7)cos(4pi/7)=-1/8,

RD SHARMA ENGLISH-TRANSFORMATION FORMULAE-All Questions
  1. Prove that : sin 51^0+cos 81^0=cos 21^0

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  2. Prove that: cos((3pi)/4+x)-cos((3pi)/4-x)=-sqrt(2)sinx

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  3. Prove that: cos(pi/4+x)+cos(pi/4-x)=sqrt(2)\ cos x

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  4. Prove that: sin 65^0+cos 65^0=sqrt(2)cos 20^0

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  5. Prove that: sin 47^0+cos 77^0=cos 17^0

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  6. Prove that: cos3A+cos5A+cos7A+cos 15 A=4cos4A cos5A cos6A

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  7. Prove that: \ cos A+cos3A+cos5A+cos7A=4cos A cos2A cos4A

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  8. Prove that sinA+sin2A+sin4A+sin5A=4 cos(A/2)cos((3A)/2)sin3A

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  9. Prove that: cos 20^0cos 100^0+cos 100^0cos 140^0-\ cos 140^0cos 200^0=...

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  10. Prove that: \ sin3A+sin2A-sin A=4sin A cos (A/2)cos((3A)/2)

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  11. Prove that:costhetacos(theta/2)-cos3thetacos((9theta)/2)=sin((7theta)/...

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  12. Prove that: (sin A+sin3A)/(cos A-cos3A)=cotA

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  13. Prove that: (sin9A-sin7A)/(cos7A-cos9A)=cot8A

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  14. Prove that: (sin A-sin B)/(cos A+cos B)=tan((A-B)/2)

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  15. Prove that: (sin A+sin B)/(sin A-sin B)=tan((A+B)/2)cot((A-B)/2)

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  16. Prove that: (cos A+cos B)/(cos B-cos A)=cot((A+B)/2)cot((A-B)/2)

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  17. Prove that:(sinA+sin3A+sin5A)/(cos A+cos3A+cos5A)=tan3A

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  18. Prove that: (cos3A+2cos5A+cos7A)/(cos A+2cos3A+cos5A)=(cos5A)/(cos3A)

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  19. Prove that: (cos4A+cos3A+cos2A)/(sin4A+sin3A+sin2A)=cot3A

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  20. Prove that: (sin3A+sin5A +sin7A+sin9A)/(cos3A+cos5A+cos7A+cos9A)=tan6A

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