C++ :

#include <iostream> 
#include <cstdio>
using namespace std;
int main()
{
	double r;
	double s,l;
	// cin>>r;
	r=10.2/3.14/2;
	l=2*3.1415*r;
	s=3.14*r*r;
	// printf("%.2lf\n",l);
	printf("%.2lf\n",s);
	// printf("%.2lf\n",l);
	return 0;
}

Pascal :

const
  pi=3.14;
var
c,s,r:real;
begin
c:=10.2;
r:=c/(2*pi);
s:=pi*sqr(r);
write(s:0:2);
end.