25 lines
543 B
C++
25 lines
543 B
C++
#include <iostream>
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#include <iomanip>
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#include <cmath>
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using namespace std;
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int main()
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{
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double a,b;
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double x,y;
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int n;
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cin >> n;
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while(n--&&cin >> a >> b >> x >> y)
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{
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y = y>0?y:-y;
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double f = y/x;
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double newx = sqrt(a*a*b*b/(b*b + f*f*a*a));
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double newy = f*newx;
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newx = newx/a*b;
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newy /= b;
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newx /= b;
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double t = acos(newx);
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double area = t * b * a / 2;
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cout << fixed << setprecision(2) << area << endl;
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}
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}
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