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Show that cos Acos ((pi)/(3)+A)cos ((pi)...

Show that `cos Acos ((pi)/(3)+A)cos ((pi)/(3)-A)=(1)/(4) cos 3A` Hence deduce that `cos.(pi)/(9) cos. (2pi)/(9)cos. (4pi)/(9)=(1)/(8)`

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SRISIRI PUBLICATION-TRIGONOMETRIC RATIONS, TRANSFORMATIONS-LAQ
  1. Show that cos Acos ((pi)/(3)+A)cos ((pi)/(3)-A)=(1)/(4) cos 3A Hence d...

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  2. If A+B+C= 180^(@), then show that sin 2A+ sin 2B+ sin 2C =4 sin A sin...

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  3. If A, B, C are angles of a triangle, then S. T sin 2A -sin 2B + sin...

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  4. If A, B, C are angles of a triangle , prove that cos 2A - cos 2B + ...

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  5. If A , B , C are angles in a triangle , then prove that sin A + sin ...

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  6. IF A,B,C are angles in the triangle, then prove that cosA+cosB-cosC=...

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  7. If A, B , C are angles in a triangle, then the sin ^(2)A+sin ^(2)B - s...

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  8. If A+B+ C =pi, then prove that cos ^(2) (A/2)+ cos ^(2) (B/2) +cos ^(2...

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  9. If A, B , C are angles of a triangle, then P. T sin ^(2) . (A)/(2)+ si...

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  10. In triangle ABC, prove that cos .(A)/(2)+cos.(B)/(2)+cos. (C)/(2) =4 c...

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  11. If A, B, C are the angles in a triangle then prove that sin .(A)/(2)+...

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  12. If A+B+C=(pi)/(2), then prove that cos 2A + cos 2B + cos 2C=1+4 sin A ...

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  13. If A+B+C=(pi)/(2), then prove that sin ^(2) A+ sin ^(2) B + sin ^(2) C...

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  14. If A+B+C=(3pi)/(2), prove that cos 2A+ cos 2B+ cos 2C=1-4 sin A sin B ...

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  15. If A+B+C=(3pi)/(2), prove that cos ^(2)A+ cos ^(2) B- cos ^(2)C=-2 cos...

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  16. If A+B+C=0, then prove that cos ^(2)A+ cos ^(2) B + cos ^(2) C =1+2 co...

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  17. If A+B+C = 2S , then P.T cos(S-A)+cos(S-B)+cos(S-C)+cosS=4cos.(A)/(...

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  18. If A+B+C+D=360^(@), the prove that cos 2A + cos 2B + cos 2C + cos 2D =...

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  19. Find the value of 2(sin^(6)theta+cos^(6)theta)-3(sin^(4)theta+cos^(4)t...

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  20. Prove that (1+cot theta -"cosec" theta ) (1+ tan theta + sec theta )=2...

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  21. If (2 sin theta )/(1+ cos theta + sin theta )=x, find the value of (1...

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