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#include <iostream>
#include <iomanip>
using namespace std;
int main(){
double R,A;
cin >> R;
A = 3.14159 * R * R;
cout << "A=" << fixed << setprecision(4) << A << endl;
return 0;
}
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#include <iostream>
#include <cmath>
using namespace std;
int main() {
cout << "Radius: ";
double r;
cin >> r;
double area = 3.146 * pow(r, 2);
cout << "The area of the circle is " << area << endl;
}