radian : Java Glossary

A unit of angular measure. A complete circle is 2π radians. One radian is about 57.2957795 degrees, measured counterclockwise from due east. Java’s Math.sin and Math.cos etc. work in radians.

There are two java.lang. Math convenience methods for interconverting degrees and radians.

// built-in radians <-> degrees methods.
public static double toDegrees ( double angleInRadians );
public static double toRadians ( double angleInDegrees );