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Show that cos 42^(@) + cos 78^(@) + cos ...

Show that `cos 42^(@) + cos 78^(@) + cos 162^(@) = 0`

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SRISIRI PUBLICATION-IPE SCANNER (TEXUAL BITS)-Very Short Questions (2 marks) (Trigonometric Ratios, Transformations)
  1. Find the value of tan 10^(@) + tan 35^(@) + tan 10^(@) . tan 35^(@)

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  2. Prove that tan 50^(@) -tan40^(@)-2tan10^(@).

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  3. Show that cos 42^(@) + cos 78^(@) + cos 162^(@) = 0

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  4. Prove that (cos9^(@)+sin9^(@))/(cos9^(@)-sin9^(@))=cot36^(@)

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  5. Find the period of f(x)=cos ((4x+9)/(5))

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  6. Find the value of cos^(2)52(1^@)/(2) - sin^(2)22 (1^@)/2

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  7. Find the period of tan(x+4x+9x+.......+n^2x) (n any positive integer)

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  8. Find a cosine function whose period is 7.

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  9. Find a sine function whose period is 2//3.

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  10. Find the maximum and minimum value of f(x) = 5sinx + 12cos x -13.

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  11. Show that cot.(pi)/(20). cot .(3pi)/(20). cot.(5pi)/(20). cot .(7pi)...

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  12. Find the value of sin^(2)""(pi)/(10)+sin^(2)""(4pi)/(10)+sin^(2)""(6pi...

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  13. Show that cos^(2)""(pi)/(10)+cos^(2)""(4pi)/(10)+cos^(2)""(6pi)/10+cos...

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  14. Evaluate cos^(2)45^(@)+cos^(2)135^(@)+cos^(2)225^(@)+cos^(2)315^(@).

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  15. If tan20^(@) = lambda then show that (tan 160^(@) -tan 110^(@))/(1+tan...

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  16. If tan20^(@)=p then prove that = (tan610^(@)+tan700^(@))/(tan 560^(@)-...

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  17. If "sec" theta + tan theta = 2//3, then find the value of sin theta an...

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  18. If "sec" theta + tan theta = 5 then find sin theta and determine the q...

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  19. If cosec theta + cot theta =1//3, then find cos theta and determine th...

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  20. If acos theta -bsin theta =c, then show that asine theta + bcos =pm s...

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