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anonymous

  • one year ago

In triangle ABC, a = 3, b = 5, and c = 7. Find the approximate value of angle A. 22° 38° 142° 158°

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  1. johnweldon1993
    • one year ago
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    We can use the law of cosine here we know \[\large a^2 = b^2 + c^2 - 2bc \times cos(A)\] So since we want to solve for A we need to rearrange this into \[\large A = \arccos(\frac{a^2 - b^2 - c^2}{-2bc})\] So just plug in everything you have and solve

  2. anonymous
    • one year ago
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    what is arccos

  3. johnweldon1993
    • one year ago
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    the inverse cosine function also known as \(\large cos^{-1}\)

  4. anonymous
    • one year ago
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    okay and i just got .92

  5. anonymous
    • one year ago
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    btw i dont have an actual calculator

  6. johnweldon1993
    • one year ago
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    The 0.92 is what you get when you do everything in the parenthesis...now you just need the inverse cosine of that Which, since you dont have a calculator...comes out to 21.786

  7. johnweldon1993
    • one year ago
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    So that would lead to your "approximate" answer to be 22 degrees

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