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Math Help - trig problem

  1. #1
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    trig problem

    i have a triangle with all angles and one side given. i need to find the other sides but dont know the steps to do so
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  2. #2
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    Use law of sines. Given a triangle ABC, side a is opposite angle A, side b is opposite angle B, side c is opposite angle C, then Law of Sines state that:

    \frac{\sin{A}}{a} = \frac{\sin{B}}{b} = \frac{\sin{C}}{c}
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  3. #3
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    so if i have angles 38, 55, and 87 degrees and angle 38 has the given side of 500 meters opposite how would i set it up?
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  4. #4
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    \frac{\sin{38}}{500} = \frac{\sin{55}}{x}

    Solving for x yields the value of the side opposite angle 55.
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  5. #5
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    ok i got answers of 665.26 and 811.02 but when i use path. theorm it doesnt work out. did i do somethin wrong?
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  6. #6
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    Quote Originally Posted by erico View Post
    ok i got answers of 665.26 and 811.02 but when i use path. theorm it doesnt work out. did i do somethin wrong?
    Pythagorean theorem works only for right-angle triangles.
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  7. #7
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    ok thank you very much. i also had some trouble with another problem. its given sides are BC 160, AD 270, and DC 190. it also has angles ADC 75 degrees and angle BCD is 90 degrees. i started by tryin to cut it to make two triangles. my separation was from angle B to D. which left me with triangles ABD and BCD. did i start off correctly?
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  8. #8
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    The Sine Rule

    For a great animated and narrated explanation of this, check out

    Mathematics.com.au - The Sine Rule

    You will understand it easily.
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