double tan(double d)

public class Test { 

   public static void main(String args[]) {
      double degrees = 45.0;
      double radians = Math.toRadians(degrees);

      System.out.format("The value of pi is %.4f%n", Math.PI);
      System.out.format("The tangent of %.1f degrees is %.4f%n", degrees, Math.tan(radians));
   }
}

The value of pi is 3.1416
The tangent of 45.0 degrees is 1.0000