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Thread: trigonometric ratios

  1. #1 trigonometric ratios 
    Forum Ph.D.
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    well, i've started understanding what sine, cosine and tangens is, basically ratios.
    now i need to understand their relations to eachother!
    gah.


    when you have eliminated the impossible, whatever remains, however improbable, must be the truth
    A.C Doyle
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  3. #2  
    Forum Ph.D. GhostofMaxwell's Avatar
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    I made up my own exaggerated pictures to remember them



    I imagine a woman with a handheld suntanning reflector, with the sunrays 1st hitting the opposite then adjacent part until she gets the tan on her face - opposite over adjacent (tan).


    I imagine a street sign with a gay guy(not PC, sorry) above a hippopotamus- opposite over hypotamus (sine)

    Then cosine is just whats left.


    Just wait to you start on sinusidal functions(cosecent, theta of the common reerance angles etc) then it gets really hard to remember.


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  4. #3  
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    hmm, yeah i know that stuff, opposite divided by hypotenuse, to get sine, adjacent divided by hypotenuse to get cosine, and opposite divided by adjacent to get tangent.
    soh cah toa.

    lately i learned that you use sine as a function, with the degrees and radions.
    and i know that nowadays, all you have to do is press sin on the calculator and add
    the degrees or radians.
    but what is the math behind the sin function on calculators?
    finding the lenghths of the triangle and such.
    when you have eliminated the impossible, whatever remains, however improbable, must be the truth
    A.C Doyle
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  5. #4  
    Forum Ph.D. GhostofMaxwell's Avatar
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    Simply: If you plot a 360 degree circle with theta against its corresponding trigonometric ratio(i.e. tan theta on x, opp/adj on y, you get a sinusoidal graph with an amplitude of "1".
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  6. #5  
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    hmm, ok, i figured out why the function of sine didn't seem very logical to me.

    heres why.



    to find sin, i need to know what cosine is.
    to find cosine, i need to know sine..
    hmm... wait a sec. it doesnt matter how long a side is, in a right angled
    rectangle, as long as i know the length of hypotenuse, and the angle!
    when you have eliminated the impossible, whatever remains, however improbable, must be the truth
    A.C Doyle
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  7. #6  
    Forum Ph.D. GhostofMaxwell's Avatar
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    Quote Originally Posted by dejawolf
    hmm, ok, i figured out why the function of sine didn't seem very logical to me.

    heres why.



    to find sin, i need to know what cosine is.
    to find cosine, i need to know sine..
    hmm... wait a sec. it doesnt matter how long a side is, in a right angled
    rectangle, as long as i know the length of hypotenuse!
    .....And the angle of that hypotenuse as well but, yeah you could rearrange the adjacent as the subject of the cosine ratio, and rearrange the opposite as the subject of the sine ratio, to deduce the sides of a rectangle, yes.
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