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Math Help - some more rt triangle trig

  1. #1
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    some more rt triangle trig

    so there is a right triangle
    90 degrees on the bottom left 39 on the bottom right
    and 12.1 in length of the hypotenuse
    im told to look for all side
    i tried using cosine and sine but my answers were
    larger than the hypotenuse
    any ideas?
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  2. #2
    A Plied Mathematician
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    How did you set up your equations? Did you make sure your calculator was in degree mode?

    Excellent checking, by the way! That's the right instinct.
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  3. #3
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    Quote Originally Posted by gabriel View Post
    so there is a right triangle
    90 degrees on the bottom left 39 on the bottom right
    and 12.1 in length of the hypotenuse
    im told to look for all side
    i tried using cosine and sine but my answers were
    larger than the hypotenuse
    any ideas?
    so, how did you set up those equations?
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  4. #4
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    Quote Originally Posted by gabriel View Post
    so there is a right triangle
    90 degrees on the bottom left 39 on the bottom right
    and 12.1 in length of the hypotenuse
    im told to look for all side
    i tried using cosine and sine but my answers were
    larger than the hypotenuse
    any ideas?
    If your answers were larger than the hypotenuse,
    then after

    sin39^o=\frac{opposite}{hypotenuse}=\frac{a}{12.1}

    you should get "a" by multiplying both sides by 12.1.

    Did you end up with a=\frac{12.1}{sin39^o} instead?


    Also

    cos39^o=\frac{adjacent}{hypotenuse}=\frac{b}{12.1}

    so you get "b" by multiplying both sides by 12.1.

    You will get a value larger than the hypotenuse if you look for \frac{12.1}{cos39^o} instead.

    Why is that and why multiply both sides by 12.1?
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  5. #5
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    skeeter's diagram is exactly how the picture is formed
    so i tried the following
    cos(39)=b/12.1
    but now that u mention it
    i forgot to multiply "12.1" to the cos(39) and
    i saw that i screwed up the problem there resulting in 9.4 instead of 15
    so i think thats where i went wrong
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