Java - 三角形与圆形面积

package 三角形与圆面积;

import java.util.* ;

class twoArea {
double Tran_Area(double d, double h) {
return d * h / 2 ;
}
double Cir_Area(double r) {
return 3.1415926 * r * r ;
}
}

public class Area {
public static void main(String args[]) {
twoArea ans = new twoArea() ;
double area_tra = 0.0 ;
double area_cir = 0.0 ;
Scanner reader = new Scanner(System.in) ;
double d = reader.nextDouble() ;
double h = reader.nextDouble() ;
double r = reader.nextDouble() ;
area_tra = ans.Tran_Area(d, h) ;
area_cir = ans.Cir_Area(r) ;
System.out.println("三角形面积为："+ area_tra + "\n" ) ;
System.out.println("圆形面积为："+ area_cir + "\n") ;
reader.close();
}
}