public?class?t1?{
public?float?f1(float?r){
return?(float)Math.PI*(r*r);
}
public?float?f2(float?a,float?b){
return?(float)a*b;
}
public?float?f3(float?a,float?b,float?c){
float?x;
x=(a+b+c)/2;
return?(float)Math.sqrt((x-a)*(x-b)*(x-c)*x);
}
public?static?void?main(String[]?args)?{
//?TODO?自動生成的方法存根
t1?t=new?t1();
System.out.println(""+t.f1(3));
System.out.println(""+t.f2(3,4));
System.out.println(""+t.f3(3,4,5));
}
}