Java error cannot find symbol?

[jhonrtin]

/**
* Print to the screen.
*
* @author Beginner.
*/
public class Mag {


public static void main(String[] args) {

double circumference = 2 * Math.PI * radius;

System.out.println ("slant height (s): " + circumference);


}
}


I get:
Beginner.java:13: error: cannot find symbol
double circumference = 2 * Math.PI * radius;
......................................… ^

symbol: variable radius
location: class Beginner


Please help!
Thanks

 

[Leonardo74]

Add

"import java.math.*"

in your program first line.