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tanjung Group Title

Help... Prove that sin36 degrees = sqrt[10 - 2*sqrt(5)]/4

  • one year ago
  • one year ago

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  1. micahwood50 Group Title
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    HINT: 180º/5 = 36º

    • one year ago
  2. tanjung Group Title
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    next, what's formula using i do

    • one year ago
  3. micahwood50 Group Title
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    Seems like it won't help. Try this, using the formula sin (a + b) = cosa sinb + cosb sin a sin36º = 2 sin18º cos18º = 2 cos72º sin72º

    • one year ago
  4. tanjung Group Title
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    ok, i know that formula.. but i think we get the new problem... because sin/cos 18 or sin/cos 72 not eassy to get.. it's very difficul, right ?

    • one year ago
  5. micahwood50 Group Title
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    It seems so. Bump your question to get more helps. Maybe someone can help you with this.

    • one year ago
  6. tanjung Group Title
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    ok, thanks...

    • one year ago
  7. tanjung Group Title
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    @cwrw238 , @experimentX , @estudier , @Hero , @Zarkon , @sauravshakya , @all... help me please, how to get it

    • one year ago
  8. tanjung Group Title
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    any idea guys ?

    • one year ago
  9. ajprincess Group Title
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    |dw:1350231015827:dw||dw:1350231152168:dw| Use quadratic formula |dw:1350231253477:dw| |dw:1350231349862:dw|

    • one year ago
  10. experimentX Group Title
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    @ajprincess try this|dw:1350231460480:dw|

    • one year ago
  11. tanjung Group Title
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    ok, i get |dw:1350231717622:dw|

    • one year ago
  12. tanjung Group Title
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    next ?

    • one year ago
  13. tanjung Group Title
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    upss. sorry, divided 8

    • one year ago
  14. ajprincess Group Title
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    |dw:1350231971343:dw||dw:1350232035700:dw|

    • one year ago
  15. ajprincess Group Title
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    @experimentX I tried bt it is a bit complex. cos sin3x=sin108.

    • one year ago
  16. ajprincess Group Title
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    Getting it @tanjung?

    • one year ago
  17. experimentX Group Title
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    this should be simpler ... sin(3x) = sin(2x)

    • one year ago
  18. tanjung Group Title
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    not yet, what should i do after that

    • one year ago
  19. experimentX Group Title
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    since this is just double angle and triple angle ... change everything back to sin ... and remove all roots and try to factorize it.

    • one year ago
  20. ajprincess Group Title
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    |dw:1350232254804:dw|

    • one year ago
  21. tanjung Group Title
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    so, just take positive sign in sqrt ?

    • one year ago
  22. tanjung Group Title
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    i know that +- it means there are two number here. what about u for it

    • one year ago
  23. mukushla Group Title
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    with positive sign u have sin 36>1 thats impossible

    • one year ago
  24. ajprincess Group Title
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    |dw:1350233305717:dw|

    • one year ago
  25. tanjung Group Title
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    oh yea, i understand now... thank u very much for ur help , @ajprincess and @mukushla

    • one year ago
  26. ajprincess Group Title
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    yw:)

    • one year ago
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