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If theta=30^@ , verify that: (i) cos2t...

If `theta=30^@` , verify that: (i) `cos2theta=(1-tan^2theta)/(1+tan^2theta)` (ii) `cos3theta=4cos^3theta-3costheta`

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RD SHARMA ENGLISH-TRIGONOMETRIC RATIOS-All Questions
  1. Find the value of x in each of the following: tanx=sin45°cos45°+si...

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  2. If theta=30^@ , verify that: (i) tan2theta=(2tantheta)/(1-tan^2theta...

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  3. If theta=30^@ , verify that: (i) cos2theta=(1-tan^2theta)/(1+tan^2th...

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  4. If A=B=60^@ , verify that (i) cos(A-B)=cosAcosB+sinAsinB (ii) sin(A...

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  5. If A=30^@ and B=60^@ , verify that (i) sin(A+B)=sinAcosB+cosAsinB (...

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  6. Using the formula of sin(A-B)=sinAcosB-cosAsinB find the value of sin1...

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  7. In a right triangle A B C , right angled at C , if /B=60o and A ...

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  9. In a rectangle A B C D ,\ \ A B=20 c m ,\ \ /B A C=60o , calculate ...

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  10. If sin(A+B)=1 and cos(A-B)=1, 0^@ < A+Blt=90^@ , AgeqB find A and B .

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  11. If tan(A-B)=1/(sqrt(3)) and tan(A+B)=sqrt(3) , 0^@ < A+B lt= 90^@, A >...

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  18. Prove that: (i) sin35 sin55-cos35 cos55=0 (ii) (cos70)/(sin20)+(co...

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  19. Express each of the following in terms of trigonometric ratios of an...

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