 |  |
2.13. Doing Trigonometry in Degrees, not Radians
2.13.2. Solution
Use deg2rad( ) and rad2deg( ) on your input and output:
$cosine = rad2deg(cos(deg2rad($degree)));
2.13.3. Discussion
By definition, 360 degrees is equal to 2
radians, so
it's easy to manually convert between the two
formats. However, these functions use PHP's internal
value of , so you're assured a
high-precision answer. To access this number for other calculations,
use the
constant
M_PI, which is 3.14159265358979323846.
There is no built-in support for gradians. This is considered a feature, not a bug.
2.13.4. See Also
Recipe 2.13 for trig basics; documentation on deg2rad( ) at http://www.php.net/deg2rad and rad2deg( ) at http://www.php.net/rad2deg.
|  | |
| 2.12. Calculating Trigonometric Functions |  | 2.14. Handling Very Large or Very Small Numbers |
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