URAL/1294

数学题。。。

#include <iostream>
#include <cmath>
using namespace std;
const double zero=1e-6;
double a,b,c,d,x;
int main()
{
    cin >> a >> b >> c >> d;
    if (fabs(a*b-c*d) < zero)
    {
        cout << "Impossible." << endl;
        return 0;
    }
    a*=1000.0,b*=1000.0,c*=1000.0,d*=1000.0;
    x=(a*b*(c*c+d*d)-c*d*(a*a+b*b))/(a*b-c*d);
    if (x < -zero)  cout << "Impossible." << endl;
    else
    {
        cout.precision(0);
        cout.setf(ios::fixed);
        cout << "Distance is " << sqrt(x+zero) << " km." << endl;
    }
    return 0;
}
//by zzy

/*gaoshangbo*/
#include <iostream>
#include <math.h>
using namespace std;
#define ep 1e-8
int main()
{
    double a, b, c, d, ans;
    scanf("%lf%lf%lf%lf", &a, &b, &c, &d);
    a *= 1000.0; b *= 1000.0; c*= 1000.0; d *= 1000.0;
    if(fabs(c*d - a*b) < ep) printf("Impossible.\n");
    else
    {
        ans = sqrt((c*d*(a*a+b*b)-a*b*(c*c+d*d))/(c*d-a*b));
        printf("Distance is %.0lf km.\n", ans);
    }
}