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anonymous

  • one year ago

help please

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  1. anonymous
    • one year ago
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    With?

  2. anonymous
    • one year ago
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  3. campbell_st
    • one year ago
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    well you can use the law of cosines to check do you know how to use it..?

  4. anonymous
    • one year ago
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    no i dont :(

  5. jennyrlz
    • one year ago
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    sec let me see what i can remeber :)

  6. anonymous
    • one year ago
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    k

  7. anonymous
    • one year ago
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    http://mathworld.wolfram.com/LawofCosines.html

  8. anonymous
    • one year ago
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    im to lazy to draw the abc triangle lol, but that explains the law of cosines well

  9. campbell_st
    • one year ago
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    the law of cosines says \[Cos(A) = \frac{b^2 = c^2 - a^2}{2bc}\] does that help

  10. campbell_st
    • one year ago
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    you have a = 5.3, b = 7 and c = 4... plug them in and post the answer you get

  11. campbell_st
    • one year ago
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    oops should read \[\cos(A) = \frac{b^2 + c^2 - a^2}{2bc}\]

  12. jennyrlz
    • one year ago
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    ^

  13. anonymous
    • one year ago
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    oh wait is it true?

  14. jennyrlz
    • one year ago
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    ill leave it to him, he knows what he is doing :)

  15. jennyrlz
    • one year ago
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    oh he left...

  16. jennyrlz
    • one year ago
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    well why do you think it is true?

  17. jennyrlz
    • one year ago
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    he did the "hard" part the rest is algebra

  18. campbell_st
    • one year ago
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    well you need to find the angle measure using the law of cosines to see if its true or not

  19. campbell_st
    • one year ago
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    an alternative solution is to google a triangle solver put in the 3 sides and then look at the angles that are calculated

  20. anonymous
    • one year ago
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    which law of cosine should i use

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  21. jennyrlz
    • one year ago
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    if only i wouldve thought of this when i was taking pre-calc...

  22. campbell_st
    • one year ago
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    use the one I posted above

  23. anonymous
    • one year ago
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    how do i use it....do i sub

  24. campbell_st
    • one year ago
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    and look for the measures that match the labels a, b and c

  25. campbell_st
    • one year ago
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    a = 5.3 b = 7 and c = 4 like this \[cos(\theta) = \frac{7^2 + 4^2 - 5.3^2}{2 \times 7 \times 4}\]

  26. anonymous
    • one year ago
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    doin the math.....

  27. anonymous
    • one year ago
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    \[\cos \theta \frac{ 49+16-28.09 }{66 }\] thats what i have so far

  28. anonymous
    • one year ago
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    is it right

  29. anonymous
    • one year ago
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    so far

  30. campbell_st
    • one year ago
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    well I think the denominator is 56

  31. campbell_st
    • one year ago
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    2 x 4 x 7 = 56

  32. anonymous
    • one year ago
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    oh yea

  33. anonymous
    • one year ago
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    wait so it is true?

  34. campbell_st
    • one year ago
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    not yet, if you do the calculation you'll find \[\cos(\theta) = 0.659107\] so to find the angle, using a calculator its \[\theta = \cos^{-1}(0.659107)\]

  35. anonymous
    • one year ago
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    i got 0.79053943 ? how do i punch this equation in a calculator

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