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Evaluate the following: sin 78^0cos 18^0...

Evaluate the following: `sin 78^0cos 18^0-cos 78^0sin 18^0`

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RD SHARMA ENGLISH-TRIGONOMETRIC RATIOS OF COMPOUND ANGLES-All Questions
  1. If sinA=1/2,cosB=(sqrt(3))/2, where pi/2 lt A lt pi and 0 lt B lt ...

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  2. If sinA=1/2,cosB=(sqrt(3))/2, w h e r epi/2 lt A lt pi and 0ltBltpi/2...

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  3. Evaluate the following: sin 78^0cos 18^0-cos 78^0sin 18^0

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  4. Evaluate the following: sin 36^0cos9^0+cos36^0 sin9^0

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  5. Evaluate the following: cos 47^0cos 13^0-sin 47^0 sin 13^0

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  6. Evaluate the following: cos 80^0cos 20^0+ sin 80^0 sin 20^0

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  7. If cos A=-12/13 and cotB=24/7 where A lies in second quadrant and B li...

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  8. Prove that: cos 105^@+cos15^@=sin 75^@-sin 15^@

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  9. Prove that: (tanA+tanB)/(tanA-tanB)=sin(A+B)/(sin(A-B)

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  10. Prove that: (cos 11^@+"sin"11^@)/(cos 11^@-"sin"11^@)=tan 56^@

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  11. Prove that: (cos8^@+"sin"8^@)/(cos8^@-"sin"8^@)=t a n 53^@

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  12. The value of : (cos9^@+sin9^@)/(cos9^@-sin9^@) is:

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  13. Prove that: sin(60^0-theta)cos(30^0+theta)+cos(60^0-theta)sin(30^0+the...

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  14. Prove that: sin((4pi)/9+7)cos(pi/9+7)-cos((4pi)/9+7)sin("pi/9+7)=(sqrt...

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  15. Prove that: sin((3pi)/8-5)cos( pi/8+5)+cos((3pi)/8-5)sin(pi/8+5)=1

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  16. Prove that :(tan69^@+tan 66^@)/(1-tan 69^@tan66^@)=-1

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  17. If tanA=5/6 and tanB=1/(11),\ p rov e\ t h a t\ A+B=pi/4

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  18. If tanA=m/(m-1)\ a n d tanB=1/(2m-1), then prove that A-B=\ pi/4

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  19. Prove that: cos^2 45^0-sin^2 15^0=(sqrt(3))/4

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  20. Prove that: sin^2(n+1)A-sin^2n A="sin"(2n+1)Asin A

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