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Math Help - Finding Sin, Cos, and Tan

  1. #1
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    Finding Sin, Cos, and Tan

    This is what I know:



    I figured out the ninety degrees and the seventy degrees because a right angle is always ninety degrees and a triangle always adds up to one hundred eighty degrees. The problem itself just told me "A= 20 degrees and a = 12" and gave me a triangle with letters..

    It doesn't even tell me where Theta is, which really confused me. Although, I assumed that the line with C on it was the Hypotenuse, the one with 12 was the adjacent line, and the b line being the opposite line.

    Using that, I could only kind of figure out Tan. Because it would be "b/12." And I think you could solve that by using the formula "12 (Tan 20) = b." Is that even right? Or is there a different way to solve it..?
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  2. #2
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    it's your choice as to what acute angle you want as theta ...

    if you pick theta = 70, then

    tan(70) = b/12 ... b = 12tan(70)

    if you pick theta = 20, then

    tan(20) = 12/b ... b = 12/tan(20)

    once you have b, you can use Pythagoras to find c, or ...

    sin(20) = 12/c ... c = 12/sin(20)

    or ...

    cos(70) = 12/c ... c = 12/cos(70)
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  3. #3
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    So..Sine would be 351/44, right?
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  4. #4
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    sine of what angle? please note that sine by itself means nothing.

    also, where/how did you get the numbers 351 and 44 ?
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  5. #5
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    Err...Scratch that. I messed up.
    Last edited by Shelbyrockin; September 10th 2008 at 05:05 PM.
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