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Thread: Confusion with Math.toDegrees() and Math.toRadians(). Please help.

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    Junior Member marksquall's Avatar
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    Question Confusion with Math.toDegrees() and Math.toRadians(). Please help.


    Dear administrators and members,

    A greeting of peace.

    I hope everyone is in good health upon reading this thread.

    I am currently working on a simple program that uses trigonometric laws like sine laws. I first try to write this simple codes first:

    double angle = 60;
    System.out.println( Math.sin(Math.toDegrees(angle) );

    Then the output is: 0.7475(something)

    I wonder why the output is 0.7475(something)? BUT, when I tried pressing sin 60 on my scientific calculator (in degrees mode as usual) the answer is 0.8660(something).

    Then later, I tried to use toRadians() method in Math class:

    double angle = 60;
    System.out.println( Math.sin(Math.toRadians(angle) );

    Then that is the time I got the 0.8660 (something) answer.

    I am just a little confused. My scientific calculator is in degrees mode, that is why I am expecting the same result if I will use the toDegrees() method, but why it did not?

    Please enlighten me. Did I miss something?


    Respectfully Yours,

    MarkSquall



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    Default Re: Confusion with Math.toDegrees() and Math.toRadians(). Please help.

    Hi,

    for Math.sin(doulbe a), a is an angle, in radians (pls refer to in API document), that's why sin(Math.toRadians(angle)) works.

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    Default Re: Confusion with Math.toDegrees() and Math.toRadians(). Please help.

    one more thing, following words are from API document, FYI.
    about toDegrees, "The conversion from radians to degrees is generally inexact; users should not expect cos(toRadians(90.0)) to exactly equal 0.0. "

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    Junior Member marksquall's Avatar
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    Default Re: Confusion with Math.toDegrees() and Math.toRadians(). Please help.

    Dear Ms. ivy,

    I already read the Java API documentation, and it's a great help for some useful definition. BUT, I just wondered why toRadians() is the one gave me the correct answer (as the one in my scientific calculator) than toDegrees() .

    Is it not if I press sin 60 in my scientific calculator, 60 is already (or "converted") in degrees (since my calculator is in DEG mode)?

    But anyway, a million thank you and more power.

    Warm regards,

    MarkSquall

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