How to use Math.cos() & Math.sin()?

Question

I'm using Math.cos and Math.sin but it returns me unexpected results like these:

 Angle   Sin      Cos
 354     0.8414  -0.5403
 352     0.1411   0.98998
 350    -0.958   -0.2836

Why I get these results?

For sine: Float x = (float) Math.sin ( Math.toRadians (270 degree) ) For cos: Float x = (float) Math.sin ( Math.toRadians (90 + 270 degree) ) — Bay, Oct 13 '19 at 21:32

Pubby · Accepted Answer · 2012-12-19T11:24:39.740

62

Are you trying to use degrees? Keep in mind that sin and cos are expecting radians.

Math.cos(Math.toRadians(354))

edited Dec 19 '12 at 11:24

answered Dec 19 '12 at 11:15

Pubby

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assylias · Answer 2 · 2012-12-19T11:20:24.350

17

Math.cos and Math.sin take angles in radians, not degrees. So you can use:

double angleInDegree = 354;
double angleInRadian = Math.toRadians(angleInDegree);
double cos = Math.cos(angleInRadian); // cos = 0.9945218953682733

edited Dec 19 '12 at 11:20

answered Dec 19 '12 at 11:15

assylias

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+1 or to use `Math.cos(Math.toRadians(354))` – Pshemo Dec 19 '12 at 11:19

score 5 · Answer 3 · answered Dec 19 '12 at 11:16

5

public static double sin(double a)

Parameters:
a - an angle, in radians.
Returns:
the sine of the argument.

answered Dec 19 '12 at 11:16

Nikolay Kuznetsov

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score 3 · Answer 4 · answered Oct 21 '15 at 03:25

3

You can use this also:

degrees *= Math.PI / 180;
Math.cos(degrees)

answered Oct 21 '15 at 03:25

Khuong

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I think `Math#toRadians()` is more readable but thanks for mentioning that way too ;) – Nicofisi Oct 05 '17 at 05:55

score 0 · Answer 5 · answered Apr 22 '15 at 21:18

None of the answers fitted my needs. Here's what I had:

A sinus in degree (not radiant). This is how you turn it back into a degree angle:

double angle = Math.toDegree(Math.asin(sinusInDegree));

Explanation: If you have 2 sides of a triangle, it's the only solution that worked for me. You can calcluate everything using the normal degree metric, but you have to convert the Math.asin() back to degree for the right result. :)

How to use Math.cos() & Math.sin()?

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