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:

Code :

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:

Code :

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

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.

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. "

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. :cool:

Warm regards,

MarkSquall