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If A =45^(@),then show that : cos 2A=cos...

If A `=45^(@)`,then show that : `cos 2A=cos^(2)A-sin^(2)A`

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NAGEEN PRAKASHAN ENGLISH-INTRODUCTION TO TRIGONOMETRY-Exercise 8 B
  1. Find the value of 2sin30^(@)cos30^(@).

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  2. Show that : 2tan^(2)60^(@)-6(sin^(2)45^(@)-tan^(2)30^(@))=5

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  3. Find the vlaue of 4sin^(2)30^(@)+tan^(2)60^(@)+sec^(2)45^(@).

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  4. Find the value of (sin30^(@))/(cos^(2)45^(@))-tan^(2)60^(@)+3cos90^(@)...

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  5. Evaluate : (sin^(2)30^(@)+sin^(2)45^(@)-4cot^(2)60^(@))/(2sin30^(@)cos...

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  6. (2tan3 0^(@))/(1-tan^2 3 0^(@))

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  7. Show that : cos^(2)60^(@)-sin^(2)60^(@)=-sin30^(@)

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  8. (2tan3 0^(@))/(1-tan^2 3 0^(@))

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  9. Show that : cos30^(@)=sqrt((1+cos60^(@))/(2))

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  10. Evaluate : (tan45^(@))/(2sin30^(@)-cos60^(@))

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  11. If A=30^@ verify that cos3A=4cos^3A-3cosA

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  12. If A =45^(@),then show that : cos 2A=cos^(2)A-sin^(2)A

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  13. Given A=60^(@) and B=30^(@), prove that : cos(A+B)=cosAcosB-sinAsinB

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  14. If A =30^(@),then show that : tan2A=(2tanA)/(1-tan^(2)A)

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  15. If tanA=1,then find the value of sin^(2)A+cos^(2)A+cotA.

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  16. If costheta=(sqrt(3))/(3), then find the value of sin3theta.

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  17. If tan(A+B)=sqrt(3)andsin(A-B)=(1)/(2),then find the value of tan (2A-...

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  18. If cos(A+B)=0andsin(A-B)=(sqrt(3))/(2)then find the value of tan(A-3B)...

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  19. If A+B=90^(@)andtanA=sqrt(3), then find the value of B.

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  20. If A-B=30^(@)andsinA=(sqrt(3))/(2),then find the value of B.

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